The Wizarding world that Harry and the reader return to at the start of the novel is in a state of panic: the Order of the Phoenix believes (correctly) that the Death Eaters have infiltrated the Ministry. This situation means that most people feel unable to trust each other or their government—something that, in previous installments, Dumbledore has suggested is actually a help to Voldemort, who thrives on fear and suspicion. In this landscape, Harry must lean on Ron, Hermione, and the Wizarding world at large more than ever, and the novel suggests that building community and connection is one of the most effective ways to mount a resistance movement.
Harry struggles with needing friends and help to complete his quest—his friends and the Order of the Phoenix make several jokes at Harry's expense about his unwillingness to accept help, especially when accepting help means allowing other people to put themselves in danger. Thus, accepting help from friends is one of the final things that Harry must learn before he can truly come of age. Though Harry's friends lovingly mock him for his independence, it's important to keep in mind that Harry wants to act alone in part because he does care so much for those he loves. Especially since he knows that his parents, Sirius, and Dumbledore all died to protect him, he's understandably hesitant to involve others when he knows that there's danger involved. However, Hermione and Ron are insistent that they're going to accompany Harry—and it doesn't take long for Harry to feel extremely grateful for his friends' company and the different skills they bring to the table. This is Harry's first real revelation: first, that in order to be a good friend himself, it's important to respect the autonomy of others and honor their decisions; then, that having his friends—especially Hermione—around to help with the planning and execution allows him to accomplish far more than Harry ever would've been able to by himself.
Harry, Ron, and Hermione soon discover, however, that it's a lot to ask of each other to be the only people they ever see or hear from, which is their state of affairs once they head out on the run—and especially once they obtain the locket Horcrux, which they wear for safekeeping but which makes the wearer unusually irritable and negative. At the same time, as the trio descends into bickering and pointless argument (a consequence in part of their isolation), Harry also notices that it seems as though their goal is increasingly less attainable. This sense increases after Ron, hungry and disillusioned, leaves Harry and Hermione for Bill and Fleur's cottage. The novel makes it clear that, while Ron's choice to leave was made in poor judgment, more important than the fact that he left was that he came back. With this, it suggests that the measure of a friendship's success is not necessarily whether it remains good and healthy at all times, but that friends are able to practice forgiveness and accept each other back into their lives after lapses like this.
Importantly, Ron's return doesn't just bring Ron himself back to his friends: he brings news of the outside world and introduces Harry and Hermione to Potterwatch, a password-protected radio program put out by Harry's allies in the resistance movement. Though Harry and those behind Potterwatch have certainly been on the same side the whole time, it's extremely gratifying for Harry to hear his friends' voices and have it affirmed that he's not the only person fighting Voldemort. In this way, while Ron and Hermione remain Harry's best friends and the only people Harry fully lets in on his quest, Harry begins to see the necessity of including others if he wishes to finish what he started and defeat Voldemort.
Harry is finally able to put this into practice when he returns to Hogwarts to find the final Horcrux, destroy the Horcrux he already has, and, hopefully, destroy Voldemort, as well. Though Harry once again refuses the help of many members of Dumbledore's Army who have gone into hiding in the Room of Requirement, when it becomes clear that a full-on battle is brewing and that he needs all the help he can get to fortify Hogwarts, Harry finally begins to understand the power of his community. Even though Harry doesn't share with anyone why exactly he's searching for the lost diadem that belonged to Rowena Ravenclaw, it's telling that all of his friends either offer to help him find it or throw themselves into preparing the castle for the battle to come—a necessity if Harry hopes to be successful and buy himself time to find the diadem in the first place. Because of the friendships that Harry formed with his classmates and teachers over the years, they trust him when he says he needs to perform this task—and having him around helps several former acquaintances, such as Professor Slughorn, reaffirm their commitment to the resistance movement and to Harry himself.
The final battle is, consequentially, a group effort mounted by the many people over the years who have come to love, appreciate, and trust Harry. In other words, the ensuing victory isn't something that Harry could've done alone. While killing Voldemort was certainly the most important part, that doesn't discount the fact that others dealt with Voldemort's closest followers and, in the case of Ron and Hermione, figured out how to do away with the Horcrux by getting into the Chamber of Secrets and using a basilisk fang.
In a more overarching way, Harry's victory is a testament to the power of friendship, not least because Voldemort's defeat will, in theory, usher in a new era of tolerance, kindness, and a crackdown on the kind of extremism that allowed Voldemort to rise to power in the first place. With this, the novel proposes that friendship can not just move mountains and make amazing things happen; very simply, fighting for friendship means that it will be possible for others in the future to learn the same positive lessons about friendship that Harry did.
Friendship, Community, and Resistance ThemeTracker
Friendship, Community, and Resistance Quotes in Harry Potter and the Deathly Hallows
"Harry, the time for Disarming is past! These people are trying to capture and kill you! At least Stun if you aren't prepared to kill!"
"We were hundreds of feet up! Stan's not himself, and if I Stunned him and he'd fallen, he'd have died the same as if I'd used Avada Kedavra!"
"It's traditional to give a wizard a watch when he comes of age," said Mrs. Weasley, watching him anxiously from beside the cooker. "I'm afraid that one isn't new like Ron's, it was actually my brother Fabian's and he wasn't terribly careful with his possessions, it's a bit dented on the back, but—"
Harry looked into Doge's earnest, pained face and felt, not reassured, but frustrated. Did Doge really think it was that easy, that Harry could simply choose not to believe? Didn't Doge understand Harry's need to be sure, to know everything?
"Sirius was horrible to Kreacher, Harry, and it's no good looking like that, you know it's true. Kreacher had been alone for a long time when Sirius came to live here, and he was probably starving for a bit of affection. I'm sure 'Miss Cissy' and 'Miss Bella' were perfectly lovely to Kreacher when he turned up, so he did them a favor and told them everything they wanted to know. I've said all along that wizards would pay for how they treat house-elves. Well, Voldemort did...and so did Sirius."
The rain was pounding the tent, tears were pouring down Hermione's face, and the excitement of a few minutes before had vanished as if it had never been, a short-lived firework that had flared and died, leaving everything dark, wet, and cold. The sword of Gryffindor was hidden they knew not where, and they were three teenagers in a tent whose only achievement was not, yet, to be dead.
Indeed, as Phineas Nigellus talked about Snape's crackdown, Harry experienced a split second of madness when he imagined simply going back to school to join the destabilization of Snape's regime: being fed, and having a soft bed, and other people being in charge, seemed the most wonderful prospect in the world at that moment.
Dumbledore had left them to grope in the darkness, to wrestle with unknown and undreamed-of terrors, alone and unaided: nothing was explained, nothing was given freely, they had no sword, and now, Harry had no wand. And he had dropped the photograph of the thief, and it would surely be easy now for Voldemort to find out who he was...Voldemort had all the information now...
He was not being kind or generous. As certainly as he had known that the doe was benign, he knew that Ron had to be the one to wield the sword. Dumbledore had at least taught Harry something about certain kinds of magic, of the incalculable power of certain acts.
"Sometimes I've thought, when I've been a bit hacked off, he was having a laugh or—or he just wanted to make it more difficult. But I don't think so, not anymore. He knew what he was doing when he gave me the Deluminator, didn't he?" He—well, [...] he must've known I'd run out on you."
"No," Harry corrected him. "He must've known you'd always want to come back."
He did not want to express the doubts and uncertainties about Dumbledore that had riddled him for months now. He had made his choice while he dug Dobby's grave, he had decided to continue along the winding, dangerous path indicated for him by Albus Dumbledore, to accept that he had not been told everything that he wanted to know, but simply to trust. He had no desire to doubt again; he did not want to hear anything that would deflect him from his purpose.
"You didn't hear her," said Neville. "You wouldn't have stood it either. The thing is, it helps when people stand up to them, it gives everyone hope. I used to notice that when you did it, Harry."
Dumbledore had warned him against telling anyone but Ron and Hermione about the Horcruxes. Secrets and lies, that's how we grew up, and Albus...he was a natural...Was he turning into Dumbledore, keeping his secrets clutched to his chest, afraid to trust? But Dumbledore had trusted Snape, and where had that led? To murder at the top of the highest tower...
"All right," he said quietly to the other two.
And Dumbledore had known that Harry would not duck out, that he would keep going to the end, even though it was his end, because he had taken trouble to get to know him, hadn't he? Dumbledore knew, as Voldemort knew, that Harry would not let anyone else die for him now that he had discovered it was in his power to stop it.
"And his knowledge remained woefully incomplete, Harry! That which Voldemort does not value, he takes no trouble to comprehend. Of house-elves and children's tales, of love, loyalty, and innocence, Voldemort knows and understands nothing. Nothing. That they all have a power beyond his own, a power beyond the reach of any magic, is a truth he has never grasped."
"Tell me one last thing," said Harry. "Is this real? Or has this been happening inside my head?"
Dumbledore beamed at him, and his voice sounded loud and strong in Harry's ears even though the bright mist was descending again, obscuring his figure.
"Of course it is happening inside your head, Harry, but why on earth should that mean that it is not real?"