The previous installment of the Harry Potter series, Harry Potter and the Goblet of Fire, ended with a major traumatic experience for Harry: he witnessed Voldemort return to his body and kill Harry's friend and classmate, Cedric Diggory. Hours afterward, Harry's trauma is compounded when Cornelius Fudge, the Minister of Magic, refuses to believe that Voldemort returned, thereby invalidating Harry's experiences and, thanks to the newpaper articles published by Rita Skeeter that called Harry's mental stability into question, discrediting his story among many in the Wizarding world. Order of the Phoenix picks up a month later, during which time Harry has received little meaningful communication with his friends and has had no opportunity to process his experiences. By illustrating how this silence makes Harry feel isolated and unsupported and leads him to question his sanity, Order of the Phoenix makes the case that the only effective way to heal from trauma like Harry’s is to talk about it. Additionally, it suggests that maintaining silence is extremely dangerous and leaves traumatized individuals vulnerable to manipulation.
It's important to note that while Harry goes back and forth about whether or not he wants to speak about what happened when Cedric died, his anger and his sense of betrayal by the adult mentors in his life, namely Dumbledore and Sirius, suggest that deep down, Harry desperately wants to be taken seriously and have someone listen to his story. In part because Harry is naturally somewhat suspicious of adult authority figures and in part because of this experience of being ignored by them, he finds that the only place he can turn to reliably seek relief is his friends, Ron and Hermione. However, though Ron and Hermione are the only characters who consistently listen to and support Harry, they are, importantly, children just like Harry is--they don't have the knowledge, skills, or adult maturity to give Harry any new information that might help him understand what's going on. This lack of support, in addition to Dolores Umbridge's campaign to torture Harry and the Daily Prophet's summer campaign of turning Harry into a joke, makes Harry feel isolated and as though he can't trust anyone--a situation that in turn makes him feel as though he has to take matters into his own hands.
By illustrating how antagonistic Ministry-affiliated individuals as well as adult mentors whom Harry trusts all make Harry feel isolated and unsupported, the novel suggests that where trauma is concerned, intention doesn't matter. Though both Sirius and Dumbledore act in ways that they believe will ultimately protect Harry, their actions do just as much harm, at least on an emotional level, as the Ministry's do. When Harry tries to tell Sirius about his disturbing "nightmare" of being the snake that attacks Mr. Weasley, Sirius brushes Harry's concern off and suggests that Harry is just overtired. Again, though it's unclear whether Sirius responds in this way because Dumbledore told him to, because he truly thinks Harry is overtired, or because he thinks he's being soothing by insisting it's not a big deal, it ultimately doesn't matter--the fact remains that this response encourages Harry to question his own sanity. In addition, not having any information about the true significance of his dreams means that Harry doesn't take Dumbledore's insistence that Harry take lessons in Occlumency (a branch of magic that protects one's mind from attack) with Snape seriously. Dumbledore reveals too late that the Occlumency lessons were intended to protect Harry from possession or manipulation, information that may have impressed upon Harry the importance of dedicating himself to learning to close his mind.
Because of Harry's isolation and his belief that what he sees in these "dreams" is entirely true (which seems to be confirmed for Harry after the snake dream, as Mr. Weasley does suffer a dangerous snake bite), Harry rushes to the Ministry of Magic with his friends when he dreams that Voldemort has Sirius there and is torturing him. This is eventually revealed to be a trap, and in the ensuing battle between the Order of the Phoenix and the Death Eaters, Sirius dies. During Dumbledore and Harry's discussion later, Dumbledore takes the blame for what happened and suggests that his choices to ignore Harry this year and deny Harry pertinent information in years past is directly responsible for Sirius's death. Dumbledore explains that the "dreams" Harry has are actually the result of a connection to Voldemort, and Voldemort is now aware of this and used the connection to plant the dream that he was torturing Sirius. Because none of the adults in Harry's life ever shared this with Harry, Harry never knew that such a thing was possible. Because Harry was silenced and lacked support from the adults in his life, he became an easy target for Voldemort. While Harry’s trauma creates psychological disturbance of a magical nature, it seems that Rowling may also be suggesting that non-magical trauma in the real world can have similarly dire consequences when it’s not processed in a supportive environment.
Further, Dumbledore also explains that Voldemort tried to kill Harry as a baby because of a prophecy that says that at some point, either Harry or Voldemort has to kill the other. By giving Harry this information, Dumbledore enables Harry to make sense of past events and also helps him understand what his future holds. In this way, the novel ultimately asserts the necessity of honesty, conversation, and shared knowledge, and suggests that they're essential to beginning to heal from trauma. It also makes it very clear that developing this openness with Dumbledore in particular is an essential element of Harry's journey forward.
Trauma, Silence, and Speech ThemeTracker
Trauma, Silence, and Speech Quotes in Harry Potter and the Order of the Phoenix
And then, as his feeling of frustration peaked, his certainty leaked away.
Perhaps it hadn't been a magical sound after all. Perhaps he was so desperate for the tiniest sign of contact from the world to which he belonged that he was simply overreacting to perfectly ordinary noises. Could he be sure it hadn't been the sound of something breaking inside a neighbor's house?
"I know, Harry. But you see what they're doing? They want to turn you into someone nobody will believe. Fudge is behind it, I'll bet anything. They want wizards on the street to think you're just some stupid boy who's a bit of a joke, who tells ridiculous tall stories because he loves being famous and wants to keep it going."
"Is it true that you shouted at Professor Umbridge?"
"Yes," said Harry.
"You called her a liar?"
"You told her He-Who-Must-Not-Be-Named is back?"
Professor McGonagall sat down behind her desk, frowning at Harry. Then she said, "Have a biscuit, Potter."
"'Hogwarts is a school, not an outpost of Cornelius Fudge's office,' said Madam Marchbanks. 'This is a further disgusting attempt to discredit Albus Dumbledore.' (For a full account of Madam Marchbanks' alleged links to subversive goblin groups, turn to page 17)."
A great wave of relief broke over Harry. Here at last was proof that he had not imagined these creatures, that they were real: Hagrid knew about them too. He looked eagerly at Ron, but Ron was still staring around into the trees and after a few seconds he whispered, "Why doesn't Hagrid call again?"
Don't be stupid, you haven't got fangs, he told himself, trying to keep calm, though the hand on his butterbeer was shaking. You were lying in bed, you weren't attacking anyone...
But then, what happened in Dumbledore's office? he asked himself. I felt like I wanted to attack Dumbledore too...
"But that's not all, said Harry in a voice only a little above a whisper. "Sirius, I...I think I'm going mad...Back in Dumbledore's office, just before we took the Portkey...for a couple of seconds there I thought I was a snake, I felt like one—my scar really hurt when I was looking at Dumbledore—Sirius, I wanted to attack him—"
He could only see a sliver of Sirius's face; the rest was in darkness.
"It must have been the aftermath of the vision, that's all," said Sirius. "You were still thinking of the dream or whatever it was and—"
"It wasn't like that," said Harry, shaking his head. "It was like something rose up inside me, like there's a snake inside me—"
"You need to sleep," said Sirius firmly.
"So that's it, is it?" he said loudly. "Stay there? That's all anyone could tell me after I got attacked by those dementors too! Just stay put while the grown-ups sort it out, Harry! We won't bother telling you anything, though, because your tiny little brain might not be able to cope with it!"
He could abandon the plan and simply learn to live with the memory of what his father had done on a summer's day more than twenty years ago...
And then he remembered Sirius in the fire upstairs in the Gryffindor common room... "You're less like your father than I thought...The risk would've been what made it fun for James..."
But did he want to be like his father anymore?
"I'm trying to say—Voldemort knows you, Harry! He took Ginny down into the Chamber of Secrets to lure you there, it's the kind of thing he does, he knows you're the—the sort of person who'd go to Sirius's aid! What if he's just trying to get you into the Department of Myst—"
"Like the fact that the person Sirius cared most about in the world was you," said Dumbledore quietly. "Like the fact that you were coming to regard Sirius as a mixture of father and brother. Voldemort knew already, of course, that Sirius was in the Order, that you knew where he was—but Kreacher's information made him realize that the one person whom you would go to any lengths to rescue was Sirius Black."
"Sirius did not hate Kreacher," said Dumbledore. "He regarded him as a servant unworthy of much interest or notice. Indifference and neglect often do much more damage than outright dislike...the fountain we destroyed tonight told a lie. We wizards have mistreated and abused our fellows for too long, and we are now reaping our reward."
"I cared about you too much," said Dumbledore simply. "I cared more for your happiness than your knowing the truth, more for your peace of mind than my plan, more for your life than the lives that might be lost if the plan failed. In other words, I acted exactly as Voldemort expects we fools who love to act."