Harry feels dirty and tainted by Voldemort. He wonders if Dumbledore won't look at him because he expects to see Voldemort in his eyes. Harry wonders if he is the "weapon" the Order is trying to keep from Voldemort, and thinks that he did attack Mr. Weasley. Mrs. Weasley sends Harry to bed when they get home, but Harry tries not to sleep. He wonders if Voldemort is an Animagus and if they both transform when Voldemort possesses him. Panicking suddenly, Harry realizes that if Voldemort is possessing him, he needs to leave Grimmauld Place to protect the Order and Hogwarts to protect his classmates. He begins to pack his trunk, but the portrait of Phineas in Harry's bedroom lazily taunts him and then gives him a message from Dumbledore: stay put.
Note how strong Harry's instinct is to protect the people and the causes he loves, even at his own risk. This reminds the reader that Harry is someone who cares deeply for others and at times, is able to care more for others than for his own happiness or comfort. That Dumbledore is sending messages through portraits, not in his own words, gives Harry what feels like even more proof that Dumbledore doesn't truly care about him or want to share any useful information with him.
Suddenly, Harry is extremely angry. He shouts that all anyone tells him is to stay put and let the adults sort it out. Phineas says he hated teaching because of kids like Harry, points out that Dumbledore has always kept Harry safe, and says that Harry is stupid for thinking that he's the only one clever enough to figure out what Voldemort is planning. Harry lies down on his bed, afraid to sleep, but he falls asleep and again finds himself walking down a dark corridor in pursuit of something. Harry stays in bed all night, half awake, feeling unclean.
Harry's anger is understandable, though it also comes out similarly to the typical teenage angst that Phineas mocks. Even if this is something that requires the adults to truly deal with the aftermath, not giving Harry any insight into what's happening to his mind and body means that Harry won't be able to appropriately interpret his experiences in the future.
Harry stays in his room until the next evening while everyone else decorates for Christmas. He's with Buckbeak when Hermione arrives and explains that skiing wasn't fun, so she ended her trip with her parents early. Harry follows her to the second floor where Ron and Ginny are waiting. Harry angrily says he doesn't want to talk, but Ginny points out that she's been possessed by Voldemort and can tell Harry how it feels. When Ginny learns that Harry doesn't have any blanks in his memory, she declares that Voldemort hasn't possessed him. Hermione also notes that Voldemort can't move Harry in and out of Hogwarts, all of which is comforting for Harry.
Though it's impossible for Harry's peers to truly interpret what's happening in his mind, Ginny and Hermione show here that they're not entirely useless when it comes to helping Harry make sense of his experiences. This impresses on Harry the importance of asking at least his peers for help, as they have more information and insight into how things work than Harry often gives them credit for.
Sirius throws himself into making Christmas a holiday to remember. On Christmas morning, Fred and George tell Ron and Harry that Mrs. Weasley is crying because Percy sent back the sweater she knitted for him. Harry and Ron accompany Hermione to the boiler room so she can give Kreacher a patchwork quilt, but he isn’t there. Harry notices that Kreacher has saved some of the family photos. Sirius and the trio discuss the fact that nobody has seen Kreacher for a few days, and Harry asks if Kreacher left the house. Sirius isn't concerned.
Again, Harry's concern about Kreacher will later turn out to be correct—but because he's a child suggesting things to knowledgeable adults, his questions aren't taken seriously. Even beloved and trustworthy adults like Sirius can devalue information from others as Harry and young people are.
After lunch, everyone goes to St. Mungo's to visit Mr. Weasley. Mr. Weasley seems strangely hearty and Mrs. Weasley looks suspiciously at his fresh bandages. He finally explains that the trainee Healer suggested they experiment with stitches—a Muggle treatment. The children excuse themselves as Mrs. Weasley learns what stitches are and starts to shout. Harry, Ron, and Hermione head for the tearoom, but on the fourth-floor landing, they come face to face with Professor Lockhart. He offers them his autograph but doesn't remember teaching at Hogwarts. A motherly Healer guides him back to his ward and invites the trio to stop in for a real visit.
Inadvertently with Professor Lockhart is a callback to the second book, and reinforces for Harry, Ron, and Hermione that their world isn't actually as large as they might think—their lives are entwined with others in unexpected ways, and they cannot move through the world expecting to be entirely anonymous. As usual, Mr. Weasley’s fascination with Muggles is treated humorously, though here it backfires and negatively affects his health.
The Healer settles them all in Lockhart's ward next to Broderick Bode, who she says is improving but not yet speaking. Lockhart starts to sign photos of himself as the Healer gives Bode a potted plant. Harry then spins around and sees Neville and his gran. Harry realizes that it must be Neville's parents in the end beds and tries to stop Ron, but Ron greets Neville brightly. Neville's grandmother greets the trio as well, but when she learns that they don't know about Neville's parents, she insists that he should be proud that they sacrificed themselves. Alice Longbottom shuffles forward and gives Neville a gum wrapper. He looks defiantly at Harry, Ron, and Hermione and then slips the wrapper into his pocket. After Neville and his gran leave, Harry heavily explains that Bellatrix Lestrange tortured the Longbottoms into insanity.
In this tragic scene, the reality of war’s aftermath becomes abundantly clear, as Neville must live with parents who can no longer care for him or even function because of the role they played in fighting Voldemort. Neville also clearly processes his trauma by staying silent and keeping his experience a secret. This makes him feel secure, but it also possibly prevents him from receiving help and support from others. The brief mention of Bode and the potted plant will become important later.