Muggles' Guide to Harry Potter/Major Events/Harry-Voldemort Shared Thoughts
|Muggles' Guide to Harry Potter - Major Event|
|Harry - Voldemort Shared Thoughts|
|Time Period||Throughout the series|
|Important Characters||Harry, Voldemort|
Throughout the series, Harry experiences dreams which, as Professor Dumbledore says, are no ordinary dreams. In most cases, these turn out to be inadvertent leakage from Voldemort's mind to Harry's. In some cases, they serve to mislead Harry; in other cases, they give Harry vital information about Voldemort's plans.
Harry's visions of what is happening in Voldemort's mind are always accompanied by pain in the lightning-bolt shaped scar on his forehead. The reverse is not always true; pain in Harry's scar can be triggered by Voldemort's proximity as well as the power of his thoughts and emotions. At least in the beginning, Harry is only able to sense strong emotions from Voldemort; but eventually, he becomes able to see what Voldemort is seeing and thinking.
Harry's scar pains him a number of times in this book, because by the time Harry arrives at Hogwarts, Voldemort is riding the back of Professor Quirrell's head, under his turban. The only time, possibly, that Harry is able to perceive Voldemort's thoughts, is in an odd dream that Harry has on the first night he is at school. During the night, Harry has a dream, involving Quirrell's turban and Malfoy turning into Snape, and Snape telling him that he must transfer to Slytherin house.
Harry is required to serve a detention in the Forbidden Forest, trailing a wounded unicorn. When Harry and Draco reach the unicorn, a hooded and cloaked figure is bent over it. Harry's scar suddenly pains him, to the point that he is unable to get away; Draco runs, but Firenze, appearing out of the woods, charges the cloaked figure and saves Harry.
During exams, Harry has trouble sleeping, suffering from "his old nightmare", with the addition of a hooded figure dripping blood. It is never made entirely clear what the nightmare in question is, though this may refer to the dream of Quirrell's turban from the start of the school year.
In the climactic encounter at the end of the book, it appears that Voldemort is able to read Harry's thoughts. This is not confirmed in this book, though Voldemort seems to have knowledge that cannot otherwise be explained. This may be conscious exercise of Legilimency by Voldemort, rather than the existing condition described below.
Chamber of Secrets[sửa]
With the death of Quirrell, and Voldemort's return to Albania, Harry's scar does not trouble him, and Voldemort does not have enough emotional strength for Harry to sense him. While Harry does end up battling Tom Riddle, his scar does not pain him at the time.
Prisoner of Azkaban[sửa]
Harry again does not sense Voldemort directly, as Voldemort is a disembodied spirit wandering the forests of Albania.
While Harry hears a high, shrill laugh whenever Dementors approach, and comes to the conclusion, eventually, that what he is hearing is Voldemort murdering his mother, these events did occur in Harry's actual presence, and may not be related to the link between him and Voldemort, being simply repressed memories being brought to the surface by the Dementors.
After learning of Sirius' supposed betrayal of his parents, while trying to get to sleep, Harry hears "a low, excited mutter. 'It has happened, my Lord ... the Potters have made me their Secret-Keeper ...' And then came another voice, laughing shrilly, the same laugh that Harry heard inside his head whenever the Dementors drew near..." It is interesting that this scene should appear in Harry's mind, as it did not occur when Harry was around, and as he seems to have captured the essence of Pettigrew's voice. There is a possibility here that this is actually a memory of Voldemort's that was retrieved through the same means by which the link was created.
Goblet of Fire[sửa]
The latter half of the first chapter of this story, where the aged Muggle, Frank Bryce, overhears a conversation between one "Wormtail" and his "master", interrupted by a snake who also joins the conversation, ends with Bryce's death, at which point Harry jolts awake from the pain in his scar. From the fading details of the dream, Harry apparently perceives it from an odd viewpoint; possibly partly Voldemort's, partly the snake's. We never learn exactly how much of this scene Harry witnessed; it is certainly true that the repeated mentions of Bertha Jorkins over the next few days do not spark any recognition in him. It is possible that Harry's "dream" only started at the discovery of Frank Bryce, as before that time Voldemort's emotional tension may not have been high enough to cause the vision to spill over.
It is during the discussion of this dream with Professor Dumbledore that we hear Dumbledore's theory that the scar pains Harry both when Voldemort is nearby, and when Voldemort is feeling strong emotions.
While Harry's scar does pain him a few additional times during the course of this book, Harry is unable to get more than a sense of the emotion Voldemort is feeling, until late in May. Then, Harry senses an eagle owl delivering a message to Voldemort, and sees Voldemort telling Peter Pettigrew that his mistake has been corrected, the man is dead. Despite this, however, Voldemort goes on to punish Pettigrew.
At the battle in the graveyard, Harry's scar pains him continuously; however, this is because Voldemort is near him, and Harry does not perceive any thoughts.
Order of the Phoenix[sửa]
After he is discovered lying outside the living room window listening to the news, Harry thinks to himself that he has nothing to look forward to except nightmares: either the events in the cemetery the previous summer and Cedric's death, or endless dreams of long dark hallways and locked doors, which Harry guesses are an expression of his frustration at his lack of knowledge, though for some reason they leave his scar prickling.
During the Dementor attack in Little Whinging, Harry hears high-pitched laughter. It is uncertain whether this is a current connection, or a Dementor-inspired memory; Harry has heard high-pitched laughter, and his mother screaming, in earlier Dementor attacks.
The dreams of corridors, accompanied by prickling in his scar, continue while Harry is at Grimmauld Place.
Harry has a sharp pain in his scar when he is just sitting down to lunch at Grimmauld Place after his hearing at the Ministry of Magic. Though it is not mentioned at the time, the timing is right for it to be the moment that Voldemort is informed by Lucius Malfoy of the Ministry's decision to clear Harry of all charges.
Harry's scar pains him again as he is going to bed after the party celebrating Ron and Hermione being appointed Prefects. Though it is not mentioned at the time, it is at about this time that Voldemort would have learned of the failure of his plan to use Sturgis Podmore to recover what he wanted from the Ministry. Harry that night again dreams of long corridors and locked doors, among his other nightmares.
Harry is assigned four successive days of detention, writing lines, with Professor Umbridge. At the end of that time, Umbridge takes Harry's hand to see if Harry "has got the message yet." When she touches Harry's hand, his scar hurts, accompanied by a strange feeling in his midriff. Discussing this later with Hermione, he wonders if there is some connection between Umbridge and Voldemort, and Hermione says that as Voldemort is now embodied again, he wouldn't need to control Umbridge as he had Quirrell. Harry wonders if Umbridge is under the Imperius curse. Hermione suggests Harry should tell Dumbledore; Harry angrily rejects this suggestion, probably in reaction to Dumbledore's having refused to speak to him since the beginning of summer. Harry suggests writing to Sirius, but Hermione rejects that, saying that communications from the school may be intercepted.
The next morning, Saturday morning, Harry writes to Sirius anyway, concealing his message, and sends it off with Hedwig. Sirius' head appears in the Gryffindor common room on Sunday night, and he explains to Harry that his scar hurting is likely unrelated; Umbridge is a bad enough piece of work, but Dumbledore does not feel that Umbridge is either a Death Eater, or controlled by Voldemort.
Tuesday of the following week, when Harry returns from his second round of detention, Ron and Hermione propose the idea of Harry teaching Defence Against the Dark Arts. Harry seems quite angry at the suggestion, and gets quite worked up about it, and afterwards is so tired he considers simply going to sleep in an armchair. But he eventually goes up to bed, where again he dreams of long corridors and locked doors, and wakes with his scar tingling.
In the dressing room after the first Quidditch practice with the re-formed team, Harry's scar suddenly hurts. Discussing it with Ron afterwards, he reassures Ron that this does not mean that Voldemort is near, but rather that he is having strong feelings about something. This time, Harry says, it is because Voldemort is angry: he wants something done, and it's not happening fast enough. The previous time, when Harry was in Umbridge's study, it was because he was happy; the strange feeling in his midriff was a happy feeling, and it seemed strange because he was so miserable himself at the time. The time before that, after Ron's and Hermione's party at Grimmauld Place, Voldemort had been furious. Ron says that Harry should tell Professor Dumbledore about this awareness of Voldemort's moods, but Harry refuses, saying that Dumbledore already knows. That night, Harry does fall asleep in an armchair before the Common Room fire, and dreams again about long corridors and locked doors until he is awakened by Dobby bringing Hedwig to him.
It is several months before we hear of another contact. After the final meeting of what has become Dumbledore's Army before Christmas vacation, Harry's dream changes from a nightmare about Cho Chang to the feeling of traveling, in a long, sinuous, and muscular body, down the long hallways he had previously dreamed about. As he approaches the door that had always been locked, he sees a man, partly hidden by an invisibility cloak. Enraged, he strikes at the man. Waking up in his own bed, Harry is physically ill from the pain in his scar. He now recognizes that the man that he had bitten was Mr. Weasley. Brought before Professor Dumbledore, Harry tells what he had seen, and in answer to Dumbledore's question, reveals that he did not just witness the attack, he was the snake. Dumbledore sends the occupants of two of the portraits in his study, Everard and Dilys, to investigate. Meanwhile, still without ever having looked at Harry, Dumbledore starts up one of his tiny, intricate machines, which emits a small plume of greenish smoke. The smoke forms the shape of a serpent in the air. Dumbledore says "Naturally, naturally. But in essence divided?" The smoke stream immediately splits, forming two snakes. Dumbledore shuts the machine down, and as he puts it away, Everard returns, confirming that they had found someone "down there".
Dumbledore now prepares a Portkey to take Harry and the Weasley children back to Grimmauld Place. As the Portkey activates, Dumbledore looks into Harry's eyes, and Harry's scar sears with pain again as he feels the urge rising in him to lunge at Dumbledore and sink his fangs into him.
At Grimmauld Place, he tells Sirius what had happened, and Sirius tells him not to worry about it. Harry does worry, though; thinking that he might turn into a snake and attack his friends, Harry is afraid to sleep. This fear is heightened after their first visit to St. Mungo's Hospital, where Harry and the Weasley children overhear Mr. and Mrs. Weasley discussing what happened, with Mad-Eye Moody and Tonks. Mrs. Weasley says that she thinks Dumbledore may have just been waiting for Harry to see something like this, and Moody suggests that Harry may be possessed by Voldemort.
Harry, afraid that Voldemort may be able to spy on Headquarters through his eyes, prepares to leave Grimmauld Place, but is stopped by Phineas Nigellus, who, from his portrait, passes a message from Dumbledore telling Harry to stay there. Harry figures that if he is under orders to stay there, it must be at least all right for him to sleep, so he does, again dreaming of the long corridor and the door that won't open, and is awakened by the prickling in his scar and Ron announcing dinner. Harry, still not entirely convinced that he isn't possessed, stays in the attic, away from the others, until Hermione drags him down to talk with the others. Ginny reminds him that she actually has been possessed by Voldemort and can tell Harry how it feels. Harry apologizes for having forgotten that, and then is reassured when Ginny's recollections do not match what has been happening to him.
Shortly before school starts after the Christmas break, Professor Snape arrives and says that Professor Dumbledore wishes Harry to learn Occlumency, the magical defence of the mind against external penetration. Harry is uncertain why he needs this, as he has determined that he is not being possessed by Voldemort, but Snape refuses to explain further.
Hermione later says that probably Dumbledore wants Harry to stop having these dreams about Voldemort.
When Harry attends his first Occlumency class with Snape, he notes Snape extracting memories from his own head and placing them in what he believes to be Dumbledore's Pensieve. Snape explains that Occlumency is the art of closing the mind against a Legilimens, one who can read and, sometimes, interpret what is happening inside another's mind. Though Snape says this is not mind-reading, Harry thinks it sounds a lot like it to him. Snape goes on to say that Dumbledore believes that, as a result of the curse that failed to kill Harry, there is some deeper link than usual between Harry and Voldemort, and as a result, Harry is able, when he is sufficiently relaxed, to see what is happening in Voldemort's mind. Dumbledore, he says, would like that to stop. Harry says that it has been really useful, as it saved Mr. Weasley from the snake, and Snape says that up until then, Voldemort had been unaware that the connection existed, but now that he is aware of it, he has guessed that it might go both ways, and he might use it to try to get Harry to do things.
At this point, the lesson begins, and Harry is totally unable to stop Snape from wandering through his memories. One of the memories Snape finds is the memory of Mr. Weasley taking Harry to the hearing at the Ministry of Magic. Harry suddenly realizes that the long hallway he keeps dreaming of is the hallway past the courtrooms in the Ministry of Magic. He remembers that corridor leads to the Department of Mysteries, and recognizes that Mr. Weasley was outside the door of the Department on the night the snake attacked. Harry asks Snape about the Department of Mysteries, and says that he has been dreaming about that corridor for months. As he says this, his scar starts hurting. Snape dismisses him, saying he should come back on Wednesday. As Harry leaves, he notes Snape taking memories out of the Pensieve and replacing them in his own head.
Discussing this with Ron and Hermione in the library later, Harry suggests that the thing Voldemort is looking for is probably in the Department of Mysteries. Hermione notes that almost certainly, Sturgis Podmore would have been guarding that door the night he was arrested, but cannot offer any explanation as to why Voldemort would have been trying to get through the door.
Harry, exhausted, now goes to bed, but as he steps through the door to the dorm, he is felled by the worst pain yet in his head, and hears the sound of maniacal laughter. Ron, who has followed at Hermione's request, asks what's going on, and Harry says that Voldemort is happy, really really happy; something he's been waiting for has happened. Ron says that Harry's resistance will be a bit low given what he's been through that evening. Harry, with his scar prickling, thinks that these lessons may be hurting rather than helping.
The next day, the Daily Prophet carries news of what had made Voldemort so happy: there has been a mass breakout from Azkaban, and ten prisoners, including Bellatrix Lestrange, Antonin Dolohov, and Augustus Rookwood, have escaped.
Over the next while, despite his practicing, Harry's Occlumency skills seem to decrease. Additionally, his scar, which used to prickle only after one of the bursts of emotion that he had sensed before, now seems to be mildly painful all the time, and he has odd little bursts of elation or rage that have nothing to do with what Harry is doing. Additionally, his dreams of walking down the corridor to the Department of Mysteries seem to be occurring every night, and always end with him standing longingly in front of the plain black door. Hermione suggests that it is like an illness, that has to reach a peak before it can start to get better; Ron, on the other hand, seems to think that Snape may actually be making Harry's natural defences worse, to make things easier for Voldemort. Hermione says that Dumbledore trusts Snape, and so Ron should do likewise.
In late February, following the miserable Quidditch match against Ravenclaw, Harry dreams again of the corridor and the dark door at the end of the hallway. When he reaches the door, this time it is just slightly ajar. He reaches out to push it open, but is awakened by a rasping snore from Ron.
The following Monday, after publication of Harry's interview with Rita Skeeter in the Quibbler, Harry has to leave the party in his honour because his scar is prickling. When he goes to sleep, he is immediately in a dark, curtained room facing a kneeling man. The man, addressed as Rookwood, has apparently just told him that the plan he has been following will not work. Rookwood, who seems to be afraid despite being told that he is not to blame, says that he is sure of his facts, as he used to work in the Department. Reminded that Avery had said Bode would be able to remove it, Rookwood says that Bode would have known what would happen, and likely that's why he had fought so hard against Malfoy's Imperius curse. Rookwood is dismissed, with instructions to send Avery, and in his dream Harry turns to a mirror, to find Lord Voldemort looking back at him. Panicked, he awakens screaming. Ron, who has just come up and is getting ready for bed, tries to help him; Harry explains what had just happened, and that Avery was in trouble. His explanation is cut short by the arrival of Dean and Seamus, who are also getting ready for bed. Under cover of their preparations, Ron tells Harry that he has to tell Dumbledore; Harry says that they have him learning Occlumency so he won't be able to see things like this, and so clearly don't want to know about it.
Snape, however, sees this dream in Harry's memories in an Occlumency lesson, and asks Harry about it. Harry says it is a dream he has had, and that this is the only one. Snape suggests that Harry's not having made any progress is due to his liking the feeling of being special, of knowing what Voldemort is doing. Harry retorts that reporting what Voldemort is doing is Snape's job, and Snape, after a short pause, confirms it. Later in the same lesson, Harry again experiences the long hallway, but this time the door is open when he reaches it, and he finds himself in a circular room lit by blue-flamed candles and having multiple doors. Before he can choose which door to go through, Snape breaks him out of his waking dream. The lesson is then interrupted by the confusion surrounding Umbridge's sacking of Professor Trelawney.
In April, the betrayal of Dumbledore's Army results in the attempted arrest of Professor Dumbledore by Cornelius Fudge, Umbridge, and the Aurors Dawlish and Shacklebolt. With his attackers disabled, Dumbledore tells Harry urgently that he must continue his studies of Occlumency with Snape. As Dumbledore speaks directly to him, Harry once again feels a pain in his scar and is filled with the urge to strike at Dumbledore and sink his fangs into him.
The following day, Harry again dreams of the long corridor, and finds the door to the Department of Mysteries open at the end of it. In the circular room, he opens another door and finds a room filled with odd flecks of light and a mechanical clicking noise. He does not take time to investigate but goes straight through to another door, which leads into a vast, dimly lit room full of shelves, each shelf laden with dusty, spun-glass spheres. His scar hurts, but there is something in here that he very much wants... and an escaped firework explodes, waking him up.
Harry dreads his next Occlumency class, as Snape is sure to find out how much further into the Department of Mysteries his dreams have taken him, but at the last moment Draco Malfoy interrupts, saying that Montague has turned up inside a toilet and Professor Umbridge needs Snape's help to extract him. Harry's curiosity about the thoughts Snape has been storing in the Pensieve gets the better of him. Snape, discovering him viewing these memories, orders Harry out of his office, effectively ending the Occlumency lessons. Harry has to tell Hermione that he is no longer having the funny dreams, even though he actually is, in order to cover for the fact that he is not taking Occlumency any more.
Harry feels he must discuss what he has learned from Snape's memories about his father with Sirius, who had been his father's friend. When Hermione asks him later, Harry feels he cannot discuss what he had talked about, so instead says that he was telling Sirius about Snape's decision to end the Occlumency lessons. Hermione agrees with Sirius that Harry should return, and says that she knows Harry is still having those dreams. Harry is, in fact, though he denies it; this time, he had gotten all the way to row number 97, which is apparently where whatever it is that Voldemort wants is kept.
Exhausted after watching Umbridge, with the assistance of five Aurors, sack Hagrid just after midnight, and having spent hours discussing it with the other members of Gryffindor house, Harry falls asleep shortly after starting his History of Magic OWL exam. He again dreams of the long hallway, the open door, the circular room, and the room full of spun-glass spheres, but this time, when he reaches the end of row 97, he sees Voldemort there, and a huddled figure on the floor. Harry recognizes the huddled figure as Sirius, and sees that Voldemort is torturing him to get him the thing he has been seeking. Harry awakens with an agonizing pain in his scar, and is helped out of the exam room by Professor Tofty, the examiner. When Harry refuses to go to the Hospital Wing, Professor Tofty suggests that after a little rest he could try finishing up his exam, but Harry says that he has done about as much as he is able to.
Over the next while, as Harry arranges for a distraction, breaks into Umbridge's office, is caught, helps Hermione lead Umbridge into the Forbidden Forest to be captured by the Centaurs, flies to London with the other students on Thestrals, and enters the Department of Mysteries at the Ministry of Magic, Harry's scar will continue to pain him. Harry will take this as a sign that Voldemort is still torturing Sirius. Harry dreads the moment when that pain reaches a peak, because he believes that will be when Voldemort, either having gotten what he wants, or having decided that Sirius will not give in, will kill Sirius.
As the Battle in the Ministry ends, Bellatrix escapes; Harry follows, to duel with her in the Atrium. Bellatrix demands that Harry release the Prophecy. Harry tells her that it is gone, and feels his scar flare with pain. He tells Bellatrix that Voldemort knows it is gone as well. The pain in his scar increases until Harry is almost insensible from it, as Voldemort himself arrives in the Atrium. Through the continuing pain, Harry watches Voldemort duel with Dumbledore. Eventually, Voldemort retreats. Harry, who has been kept out of the battle by an animated statue out of the Fountain of Magical Brethren, believes that the battle is over, but then his scar almost explodes with pain as Voldemort possesses him and challenges Dumbledore to kill Voldemort by killing Harry. Harry, who has just seen his godfather Sirius die, thinks of how he will be re-united in death with Sirius and his parents. Suddenly and inexplicably, Voldemort leaves his mind.
In Dumbledore's office after the battle, Dumbledore explains to Harry that he had recognized the existence of the link in previous years, and had believed that it was getting stronger since Voldemort's return. He tells Harry that the reason he had Snape teaching Harry Occlumency, rather than doing it himself, was that he believed that if Voldemort suspected there was more to the relationship between Harry and Dumbledore than that of student to Headmaster, Voldemort would use that knowledge to attack either or both of them. This is also the reason that Dumbledore had been so careful to avoid looking at Harry, or speaking directly to him, for the entire year. Dumbledore also says that it is love, in particular the love of Sirius, that had driven Voldemort out of Harry's mind in the Atrium, and it is that strength that Harry has and Voldemort does not, that will in the end allow Harry to defeat Voldemort.
Professor Dumbledore asks Harry at one point if his scar has been hurting at all. Harry says it has not, and expresses surprise. Dumbledore says he is not surprised at all; after the events at the Ministry, he believes Voldemort has determined that Harry's mind is a very uncomfortable place to be, and will choose to avoid it as much as he can.
Despite Voldemort being present in the sky above Privet Lane, Harry's scar does not start paining him until Voldemort, alerted to the identity of the real Harry, appears immediately behind him and Hagrid on the flying motorbike. Harry must duel with Voldemort and the two other Death Eaters there through the nearly blinding pain in his scar. The pain in Harry's scar continues even after Harry has passed through the protective spells around Ted Tonks' house, and to a lesser extent as Harry reaches The Burrow and waits for the other teams to return. The pain in his scar then reaches a crescendo, and, as he leaves the house for some fresh air, he sees, through Voldemort's eyes, an old man being tortured. Voldemort accuses the man, who Harry recognizes as Ollivander, of lying to him about another wand working against Harry, and Ollivander saying that the linkage exists only between Voldemort's wand and Harry's. As the vision and the pain fade, Harry sees that Ron and Hermione are at his side, and tells them what he has seen. Hermione is horrified; she is worried that Voldemort might use this channel against Harry again.
On the night before Harry turns 17, he dreams of seeing a small village, which may hold the man he seeks, at the end of a mountain road. Ron tells him that he was saying "Gregorovitch" in his sleep, over and over, and Harry says he thinks Voldemort is looking for him. Neither of them can remember who Gregorovitch is, though Ron suggests he might be a Quidditch player.
It is two days later, in conversation with Viktor Krum that Harry recalls that Gregorovitch is a wand-maker. Viktor says that he is the best, though he knows the English wizards set great store by Ollivander. Harry, understanding that Voldemort fears his wand and is trying to find a different wand that will defeat Harry's, wonders whether Gregorovitch might be able to build the stronger wand that Voldemort so clearly wants.
Shortly after the Trio evade the Death Eaters and return to Grimmauld Place, Harry's scar pains him again. Ron asks him what's wrong, and Harry says "he's very angry". Hermione, dismayed, says that she had thought that had stopped, and Harry says it has started again, mostly when Voldemort loses control. Hermione reminds Harry that Voldemort had used that channel to plant false memories in Harry before, and Harry says he remembers that very well without reminders. As the pain increases, Harry flees to the bathroom, and there, through Voldemort's eyes, he sees Draco Malfoy being compelled to torture one of the two Death Eaters for having allowed Harry to escape from the Tottenham Court Road café.
Harry's scar is quiet until a month later, when it suddenly flares up at dinnertime, possibly coincidentally just after Harry says Voldemort's name. Harry, again, goes to the bathroom, where he sees through Voldemort's eyes as he enters a village, asks the German-speaking occupants of a house there for Gregorovitch, and then murders them when they say they don't know where he moved to. Ron and Hermione hear him cry out; when Harry tells them what he has seen, Hermione again tells him that Dumbledore had wanted him to stop seeing these things. Harry retorts that he doesn't like it, but he was never any good at Occlumency, and he's going to keep on doing it because, despite his having to see what Voldemort is doing when he's at his worst, it is useful to know what Voldemort is up to.
That night, Harry wonders how long Gregorovitch can stay hidden with Voldemort seeking him so assiduously.
As it turns out, it is the following night that Harry, standing guard in the tent after their escape from the Ministry, sees through Voldemort's eyes as Voldemort interrogates Gregorovitch, examines his memory to see a thief taking something, and murders him. Hermione again says that Harry should not be seeing Voldemort's thoughts, though at Ron's bidding she does not say Voldemort's name. When Harry tries to tell her what Voldemort was doing, she dismisses him. Talking it over quietly with Ron, Harry wonders what Voldemort is after; it can't be a new wand, not if he's killing wandmakers, and Harry didn't see what the thief had stolen, so it must have been something small.
Harry finds that when he is wearing the locket Horcrux, his scar prickles more frequently. Sometimes, when it prickles most fiercely, he sees a face: always the same face, that of the young thief who had stolen the object from Gregorovitch. This disappoints Ron, who is hoping Harry's linkage with Voldemort will provide some news of his family.
When Harry and Hermione visit Bathilda Bagshot in Godric's Hollow, Harry notes the Horcrux he is wearing seems to move as he passes close to Bathilda. However, it is only when the concealed Nagini contacts Voldemort that Harry's scar prickles, and he hears Voldemort, exultant, saying "Hold him!" Not understanding what has happened, Harry turns to look where Bathilda has indicated, in hopes of finding the Sword of Gryffindor, but out of the corner of his eye sees Bathilda collapsing and Nagini emerging from her body. In the ensuing battle with Nagini, Harry is hindered by sensing Voldemort's thoughts as he flies towards Godric's Hollow, and by the locket Horcrux reacting to the approach of Voldemort, the soul from which it was sheared. Harry watches through Voldemort's eyes as he and Hermione Apparate away.
Harry now relives, in Voldemort's memory, the events of sixteen years earlier, when Harry's parents had been murdered. He watches as Voldemort murders his unarmed father and mother, and tries to murder little Harry. Still watching through Voldemort's eyes, he sees Voldemort, back in the present, finding the photo of the thief, which Harry had found in Bathilda's study and had dropped in the struggle, and he feels Voldemort's joy as he recognizes the thief in the picture. Harry returns to himself at Hermione's urging. Hermione tells him he has been insensible for hours, not unconscious, but thrashing around and saying things.
Harry's scar does not bother him again until after Ron rejoins the group, and the locket Horcrux is destroyed. When Harry's scar starts prickling again, Harry is somewhat dismayed that the visions he receives are no longer as detailed as they had been, being instead vague impressions of mountain shapes, and blames his broken wand for the loss of clarity.
However, shortly after Harry, Hermione, and Ron are captured by Snatchers, Harry's scar once more burns with pain, and Harry finds himself looking through Voldemort's eyes at a huge stone building with a tall tower. He must make the supreme effort to remain in his own mind as Voldemort flies to the top of the tower, insinuates himself within the cell at the top, and questions the man imprisoned there. The man says he knows what Voldemort has come for, but he never had it. At this point, as Harry is being dragged into Malfoy Manor, Harry finds that his fear of being identified by Lucius Malfoy makes it easier to block out Voldemort. His continuing fear allows him to continue to block Voldemort's mental images, except for one brief interval where he sees the old man in the tower cell mocking Voldemort, until Bellatrix, convinced that the sword she found the Snatchers carrying did not in fact come from her vault at Gringotts, touches her Dark Mark to summon Voldemort. The sudden surge of pain in his scar once again opens Harry's mind to what Voldemort is thinking and doing, and again Harry must do battle, this time with Bellatrix, Lucius, Narcissa, and Draco, while at the same time trying to stay in his own mind as Voldemort kills the old man, who Harry now recognizes as Grindelwald, then flies close enough to Apparate to Malfoy Manor.
After escaping from Malfoy Manor, Harry finds that his grief at Dobby's death insulates him to some extent from Voldemort's thoughts. As Harry cleans up after the burial, as he speaks with Griphook about the possibility of breaking into Gringotts, as he speaks with Ollivander about wandlore and the Elder Wand, and as he explains to Ron and Hermione what he is thinking of, his scar continues to prickle, and he has to fight the ongoing invitation to release the world he is in, to see what Voldemort is doing and thinking. Finally, beside Dobby's grave, he is once again in Voldemort's mind, and he watches as Voldemort walks the grounds of Hogwarts, as he opens Dumbledore's tomb, and as he removes the Elder Wand from Dumbledore's dead hands.
Harry's scar does not pain him again until after the escape from Gringotts. Then, as they sit on the shores of the lake treating their injuries, and watching the dragon recuperate from its long captivity, Harry is again consumed by Voldemort's anger as he discovers that the Cup Horcrux has been stolen. Harry stays in Voldemort's mind as he summons Nagini to himself and determines to check all of the places that he has hidden Horcruxes, starting with the ring, then the locket and the one hidden at Hogwarts. The diary, Voldemort knows, has been destroyed, and he believes he did not feel its destruction because he was a disembodied spirit at the time, and the Cup has now been stolen, but surely the others have not been disturbed, he would have felt it. Harry, returning to himself as Voldemort starts his flight to the Gaunt shack, tells Ron and Hermione that they must head to Hogwarts, to try and find the final Horcrux before Voldemort gets there.
Just after Harry returns to Hogwarts, and is being brought up to speed in the Room of Requirement, his scar burns fiercely again, and he suddenly is watching through Voldemort's eyes as Voldemort finds an empty golden box in the ruins of the Gaunt shack. Returning to himself by force of will, Harry tells Ron and Hermione that they are running out of time. While he tries to explain to Neville and the assembled members of Dumbledore's Army in the Room of Requirement that they have a single mission at the school and then will depart, Harry's scar continues prickling and his head continues to ache. It is shortly after he is convinced to allow the group to help him search, that his scar once again burns, and he sees Voldemort launching himself into flight. He returns to himself again, telling Ron and Hermione that Voldemort is on the move.
In the Ravenclaw common room, Harry is discovered by Alecto Carrow. When she touches her Dark Mark, Harry's scar again burns with pain, and he is once again in Voldemort's mind as Voldemort stands on a rocky outcrop surrounded by sea. Harry "hears" Voldemort thinking "Good, they have the boy," before a loud bang brings him back to himself. He finds that the noise was Luna Stunning Alecto. Harry's scar continues to throb, and he chooses to sink into Voldemort's mind while the Ravenclaw students are milling about, looking at Alecto lying on the floor. Voldemort is passing through the first cave, on his way to look at the Locket Horcrux. Harry's scar continues to throb as Professor McGonagall lets Amycus Carrow into the Ravenclaw common room, as Carrow attempts to lay blame for Alecto's Stunning and the summons to Voldemort on the Ravenclaw students, and as McGonagall refuses to allow that. Shortly after Professor McGonagall is insulted, and Harry reveals himself to her, Harry sees, in the back of his mind, Voldemort sailing fast over the lake in the cavern, and then is again taken out of himself by Voldemort's rage as he finds there is no locket within the basin in the cave.
Harry's scar continues to prickle as they meet Snape, as McGonagall and Snape duel, and as Snape departs the school. Shortly after Snape's flying departure, Harry is again in Voldemort's mind as the tiny boat returns to the shore of the cavern, and Voldemort leaps ashore. Harry's scar sears with pain again shortly after the assembled defenders leave the Room of Requirement, and through Voldemort's eyes he sees the closed gates of Hogwarts, and within them, the school.
As the battle is joined and Harry hunts the Diadem, he is too busy to notice his scar. However, when Hermione demands that he find Voldemort and Nagini, the last Horcrux, he notices that his scar has been aching for hours, trying to get him to see what Voldemort is doing. He is quickly able to get into Voldemort's mind. There, he sees Voldemort observing the battle, and repeatedly dismissing a broken Lucius Malfoy's attempts to end the battle, seeing them as attempts to save his son's life. Troubled about the wand in his hand, Voldemort tells Malfoy to bring Snape to him, then, looking at Nagini, says that it is the only way. Harry, returning to his own mind, reports that Voldemort is in the Shrieking Shack.
As Harry, from concealment, watches Voldemort conversing with Snape in the Shrieking Shack, he feels the pain in his scar building, and knows from this that Voldemort is growing angry, though nothing in his manner reveals it. Voldemort is angry that the Elder Wand, which he has located with great effort, is working no better than the wand he got from Ollivander many years before. His rage is so extreme that it once again draws Harry out of his own mind and into Voldemort's, where he is an unwilling audience as Voldemort flips the magical cage surrounding Nagini towards Snape, and orders Nagini to kill.
In Snape's memories, Harry learns that Dumbledore had believed that the link between Harry and Voldemort was more than it seemed. Dumbledore had told Snape that when Voldemort had tried to kill Harry and had failed, a fragment of his soul had been torn off and had attached itself to Harry. It was this soul fragment that provided the communications between Harry and Voldemort, and that provided Harry's ability to talk to snakes. While that soul fragment remains attached to Harry, it will work as a Horcrux, anchoring Voldemort's soul to Harry's. Thus, the only way for Voldemort to be defeated is for Harry to die at Voldemort's hand.
Voldemort's attempt to kill Harry in the Forbidden Forest sends Harry to a place that has been referred to as the Waystation by fans, and so will be called that in this work. There, Harry meets the shade of Albus Dumbledore who explains that the soul fragment within Harry had been destroyed, and thus the link between Harry and Voldemort was broken. Dumbledore explains further, or leads Harry to the understanding that Voldemort had been unable to kill Harry because Voldemort, taking Harry's blood to re-animate himself, had also taken into himself a part of the enchantment tied to Lily Potter's blood that had protected him all those years. It is thus impossible for Harry to die while Voldemort remains alive.
In the Epilogue, Harry notes that for the past nineteen years, his scar has remained quiet.
As early as Harry's first day at Hogwarts, we understand that pain in Harry's scar is connected with an enemy of Harry, and that it seems to be related to that enemy's close study of Harry. We do not know that the enemy in question is Voldemort, however, until the end of that book, when Dumbledore explains that to Harry. The linkage thus is useful for informing Harry, and us, of Voldemort's proximity, and to an increasing extent over the course of the books, his emotions.
In Harry Potter and the Order of the Phoenix, this link has two main consequences. The first occurs around Christmas, when Harry, perceiving the attack on Arthur Weasley, is able to sound the alarm. This perception allows him to save Arthur's life. However, the burst of hatred towards Dumbledore that Harry feels as he is about to use the teapot Portkey to reach Grimmauld Place leaves him worried that Voldemort may be spying on Harry's surroundings through Harry's own eyes and ears.
As far as we are able to tell, Voldemort is not ordinarily able to look through Harry's eyes. We assume, based on what we are told in the story, and on the specific times that Harry is able to see what Voldemort is seeing, that it is only when Harry is in the grip of extraordinarily strong emotion, as he is after having witnessed the attack on Arthur Weasley, that Voldemort is able to see what Harry sees. However, having once experienced Harry's view of the world, Voldemort becomes aware of the linkage. Having learned about the link, in that same book Voldemort uses it to lure Harry to the Department of Mysteries, where he was able to retrieve the Prophecy that Voldemort wanted. Harry accidentally destroyed the Prophecy, however, before it fell into Voldemort's hands. As part of that battle, and due to that same link, Harry was briefly possessed by Voldemort, who found Harry's mind an excruciatingly uncomfortable place to be, filled as it was with love (at that instant, for the departed Sirius Black) and, more, with the desire to die and join Sirius.
In Harry Potter and the Deathly Hallows, this link provides necessary information about what Voldemort is doing. Voldemort seems to be less and less capable of controlling this link as the book progresses, while Harry's control over it increases. In the absence of Dumbledore, the link is our only source of information about Voldemort's actions and plans. It is through this link that Harry learns of Voldemort's intention to visit his Horcruxes, and that provides the impetus for Harry's re-entrance into Hogwarts. And Harry, by the end of this book, is able to turn the link around and force himself to see through Voldemort's eyes; it is by means of this link that Harry is able to determine that Voldemort is hiding in the Shrieking Shack.
Harry's scar hurting has always been an indication of the activity of the link between Harry and Voldemort. As the series progresses, our understanding of the behaviour of the scar, and of the link, improves alongside Harry's.
In Harry Potter and the Philosopher's Stone, Harry's scar, we believe, indicates that Voldemort is close to Harry. In that book, whenever Harry's scar pains him, it is because Voldemort, then riding the back of Quirrell's head, is physically near him. It is particularly intense when Voldemort is studying him. We note that it doesn't always happen; when Quirrell finds Harry and Ron trying to get into the forbidden hallway in the belief that this is the shortest way to Transfiguration class, there is no mention of Harry's scar aching. We suspect that the actual reason for Harry's scar hurting is Voldemort's experiencing strong emotion because he is aware of Harry's proximity.
In Harry Potter and the Chamber of Secrets, while Voldemort is not present, an earlier fragment of his soul is there, in the form of Tom Riddle's diary. Harry's scar does not hurt, despite the proximity of the fragment of Voldemort's soul. This could be because the fragment of soul in the diary was sheared off before Harry got his scar, and therefore the resonance which causes Harry's scar to hurt is not present; the scar could possibly only sense the soul in the state it was when the scar was created, or later. However, we will later see that Harry's scar does not react directly to other Horcruxes, even those created after the scar. It is reasonably clear that Harry's scar will only react to Voldemort, not to his soul fragments, though being in close proximity to a Horcrux, we will see later, does seem to increase his sensitivity to the link.
In Harry Potter and the Goblet of Fire, we start seeing that Harry's scar is not only reacting to proximity to Voldemort, but also to Voldemort's emotional peaks and valleys, and allowing Harry to occasionally experience what is happening in Voldemort's mind. In fact, we recognize what is happening before Harry does himself. On the two occasions that Harry experiences visions of what is happening in Voldemort's mind, he tries to dismiss it as a dream, though he is not entirely successful.
Perhaps because of this, Harry does not recognize the recurring dream he is having throughout Harry Potter and the Order of the Phoenix as originating with Voldemort. In this book, Harry can see entire sequences of events as they occur to Voldemort, but does not recognize that they could be entirely fictional. As a result, Voldemort is able to plant fictions into Harry's mind, and Harry, believing them to be truth, tries to act upon them, to his detriment.
Voldemort at one point tries to take over Harry's mind in Harry Potter and the Order of the Phoenix, but finds it a very uncomfortable place to be. Harry, who has just seen his godfather die, is filled with love for Sirius and a longing for death to re-unite them. Voldemort has never felt love and so the feeling is entirely alien to him. Additionally, Voldemort fears death, and so Harry's desire for it must be not only alien but frightening to him. As a result of this, Voldemort keeps his mind closed to Harry for the entire sixth book.
Throughout the latter half of Harry Potter and the Order of the Phoenix, Dumbledore has Snape attempting to teach Harry Occlumency, in an attempt to block Voldemort from Harry's mind. There is some question as to whether this will have any effect at all. First, what Voldemort is doing is impressing images onto Harry's mind, which is rather the opposite of Legilimency; Voldemort is creating an image in his own mind, and exposing it to Harry selectively. What Harry should presumably be trained to do is to either become a better Legilimens, so that he can see the story behind the presented image, or else learn how to turn his own limited Legilimency off. Second, as Harry is not using Legilimency and is yet able to see into Voldemort's mind, there is some question as to whether Occlumency, which acts to counter Legilimency, would even work. It is possible that the link, being through the soul shard that Voldemort had left in Harry, is not actually subject to that sort of magical control.
As the channel between Harry's thoughts and Voldemort's is one of the least understood aspects of the story, at least by the protagonists, it is entirely understandable that some incorrect statements and assumptions are made about it. Most importantly, of course, is the entire issue of blocking the channel, should Harry feel the need, as discussed above. However, several minor errors have crept into the text. In particular, when Harry and Dumbledore are speaking of Harry's scar and when it hurts, Dumbledore says that he believes it hurts when Voldemort is nearby, or when he is feeling a strong emotion. Later, though, Harry says that Dumbledore had said his scar would hurt when Voldemort was nearby or feeling hatred (italics ours). Ron urges Harry at this point to tell Dumbledore that Harry is now feeling any intense emotion of Voldemort's; Harry resists. A minor plot point thus hinges on this mistake; one must wonder whether it is Harry or the author who has misremembered.
Dumbledore informs Harry in Harry Potter and the Half-Blood Prince that Voldemort has begun blocking Harry's access to Voldemort's mind by using Occlumency. However, in Harry Potter and the Deathly Hallows, Harry is regularly experiencing Voldemort's thoughts once again. No outright explanation for this development is ever provided, although the author has provided enough information to make some inferences.
In the early chapters, Voldemort attacks Harry with a borrowed wand to avoid the reverse-spell effect generated by the twin cores of their wands. Nevertheless, Voldemort fails to kill Harry; Harry's wand reacts independently and destroys Voldemort's wand. Voldemort is furious and frightened by Harry's inexplicable power and becomes desperate to find the Elder Wand, thinking he needs a supremely powerful wand that can destroy Harry's. His emotional state could explain why Harry can once again have visions of Voldemort. It was stated by Snape in Harry Potter and the Order of the Phoenix that Occlumency requires a calm mind. Voldemort, in turmoil after discovering that Harry has power he cannot counter or understand, is perhaps no longer capable of Occlumency when Harry is nearby. Indeed, every time Voldemort's thoughts impinge upon Harry, Voldemort is in the grip of rage and fear over his wand and his Horcruxes.
Alternative explanations exist. One of the characters does speculate that Voldemort is weakening, presumably as the endless murders further shred his soul, and this is certainly a possibility. Another, unexplored possibility is that the link to the soul shard in Harry becomes stronger as the other extant soul shards (the Horcruxes) are destroyed. There is clearly an ongoing link between the soul shard in Harry and the remains of Voldemort's soul; it is entirely possible that there is a similar link to each of Voldemort's Horcruxes. As the locket, the cup, and the diadem are destroyed, Harry's perceptions of Voldemort's actions seem less dependent on Voldemort's state of mind and more controllable by Harry's will. It is certainly possible that as these linkages are destroyed, the remaining ones become stronger. This is uncertain, however, as Voldemort is unable to perceive any of his Horcruxes being destroyed; with the diary, the ring, and the locket having been destroyed, the links to the cup, the diadem, Harry, and Nagini should have been strengthened, one would expect, to the point that Voldemort would perceive the destruction of the cup or the diadem. Yet he does not seem to notice either. Perhaps, though, the soul fragment in Harry is gaining strength through its attachment to Harry's complete and healthy soul.
It is through the course of Harry Potter and the Deathly Hallows, then, that Voldemort's gradual loss of self-control allows Harry to once again see what Voldemort is thinking and doing when Voldemort is at his emotional extremes. Over the course of the book, Harry, who is the stronger wizard, we are told, in part because he does not fear death, learns to control how much of Voldemort's mind he allows in. By the time he is taken to Malfoy Manor, he is able, by sheer effort of will, to keep his consciousness in the face of Voldemort's fiercest anger, and he finds that his own grief, later, as he buries Dobby, allows him to hold Voldemort's thoughts to a background level, where he is aware of them to a certain extent but is not captive to them. Harry eventually reaches a point of conscious control where he can force his way into Voldemort's mind at will.
It is perhaps an interesting side light that the course of events requires that Harry's attention be drawn away from Voldemort's mind while Voldemort is inspecting Grindelwald's memory of the duel with Dumbledore. If Harry had experienced that memory, it might have changed his understanding of Dumbledore, and perhaps brought him closer to reconciliation with Dumbledore earlier in the story. While that might have been good for Harry, it would likely have weakened the story, as one of the particularly strong areas in the story is the successive unveilings of Dumbledore's motivations, first by Aberforth in the Hog's Head, and second by the shade of Albus Dumbledore in the Waystation.
One of the questions that has been asked is, when did Dumbledore become aware of the soul shard within Harry? We can never know for certain, but we can speculate.
In Snape's memories, we learn that Dumbledore had been sure of the existence of the soul shard, since before the conversation that Hagrid had overheard in March of the previous year. (The conversation in question, where Snape produces a Patronus, occurs the evening after the conversation overheard by Hagrid and discussed with Harry and Hermione as they leave the Hospital Wing after Ron's birthday accident.) At that time, Dumbledore is aware that Harry's connection with Voldemort and his parseltongue ability are due to that shard. Note that Dumbledore never uses the word "Horcrux" to refer to the soul shard in that conversation; this is an argument that what is riding Harry is not a Horcrux, rather just an attached bit of soul.
So how far back can we take it? Certainly as far as Christmas in Harry Potter and the Order of the Phoenix. The telling point there is that Dumbledore asks what Harry's viewpoint was, and does not seem surprised to learn that it was through the snake's eyes that Harry witnessed the attack on Arthur. (The author has indicated, though she has not said outright, that the machine producing the snake-like coils of green smoke is indicating the dual-intelligence nature of Nagini, either Nagini and Horcrux in Nagini, or Voldemort in Voldemort and Horcrux.) This, for Dumbledore, would probably have been confirmation that two soul shards still existed: the Horcrux in Nagini and the shard in Harry, and would have been explanation for the abilities that Harry had shown, and the communications channel.
So when did Dumbledore really know? The appearance of Voldemort's face riding the back of Quirrell's head in Harry Potter and the Philosopher's Stone would have told Dumbledore that Voldemort knew how to make a Horcrux, and had done so. The diary in Harry Potter and the Chamber of Secrets indicated that Voldemort had made at least two. We suspect that it was over the summer that Dumbledore recognized that if he had made two, Voldemort likely made more, and that his soul could be frayed enough that a piece could shear off at his disembodiment. If it then attached to the last living being in the house, it would have ended up riding Harry, thus explaining, in particular, how a wizard with no direct bloodline back to Slytherin could speak to snakes. (While Dumbledore can speak to snakes also, in his case we believe it was through study rather than an inherent ability.) We suspect that Dumbledore was reasonably sure of the existence of the soul shard through most of Harry Potter and the Prisoner of Azkaban, but did not concern himself with it overly until he learned of Voldemort's re-embodiment at the end of Harry Potter and the Goblet of Fire.
Related to this is, of course, Dumbledore's understanding of other aspects of this interaction. We believe that Dumbledore knew, from the beginning, that Harry would have to fight Voldemort, based on the prophecy that was made before his birth. Probably, Dumbledore did not think, initially, that Harry had to die because of that. We suspect that, after the end of Harry Potter and the Chamber of Secrets, he believed that Harry would die in the encounter. When Dumbledore learns Voldemort used Harry's blood in his re-embodiment at the end of Harry Potter and the Goblet of Fire, he then believed that Harry could not be killed by Voldemort. Again, it is necessary to be careful with wording; in Snape's memories in Harry Potter and the Deathly Hallows, we hear Dumbledore say that Harry will "set out to meet his death", but he neither says that Voldemort will kill him, nor that he will die. It is Snape who says that Harry must die. Dumbledore, at this point, knows that Harry must be hit with a spell hard enough to destroy or at least detach the soul fragment, and insists that it must be done by Voldemort only because Harry is to some extent safe from Voldemort. If anyone else was to kill Harry, it would destroy the soul fragment, but if Voldemort does it, Harry is likely to survive the experience. It is quite possible, though we can of course only speculate, that Dumbledore, seeing that Snape was heavily distressed at the prospect of sacrificing Harry, calmed Snape down by letting him in on more of the secret. As Dumbledore would have done this by telling Snape that Harry would survive, but must not be told he would, for his sacrifice to have validity, we can see that Snape, even in extremis, would have wanted to keep this memory from Harry.
So, in summary: Dumbledore knows that there is at least one Horcrux by the end of Harry Potter and the Philosopher's Stone. By the end of Harry Potter and the Chamber of Secrets he knows that there are at least two, and suspects the soul shard in Harry. His belief in the soul shard is firmed up by events in Harry Potter and the Goblet of Fire, and he is quite sure of its existence by Christmas in Harry Potter and the Order of the Phoenix. Dumbledore always knew Harry and Voldemort would have to fight, but was never sure of the outcome until the end of Harry Potter and the Goblet of Fire, where he learned that Voldemort had taken Harry's blood and thus extended Harry's protection. At that point, he knew that despite Harry's vulnerability to any and all other wizards, Voldemort alone could never kill him, unless Harry allowed it; and he believed that Harry needed to be hit by a killing spell in order to destroy the soul shard. We suspect that knowing this, Dumbledore started a campaign, almost certainly with Snape's assistance, to convince Voldemort that he had to fight Harry directly. Dumbledore's program of strengthening and training Harry was specifically to make him less vulnerable to other chance encounters, and to give him the confidence in himself that would be required to allow him to face Voldemort. And it had to be kept secret from Harry, as his invulnerability to attacks from Voldemort was by no means certain; Dumbledore believed Voldemort could not kill Harry, but knew that he could certainly hurt or imprison Harry, or order some other Death Eater to kill him.