You might belong in Gryffindor, Where dwell the brave at heart, Their daring, nerve, and chivalry Set Gryffindors apart… (7.33)
Just as the Hufflepuffs are defined by their loyalty, according to the Sorting Hat, the Gryffindors are defined by their courage. Specifically, their courage, which has aspects of "daring, nerve, and chivalry," is founded in the heart – not the mind – it's emotional first, calculated second. In other words, Gryffindor bravery is sometimes brought on by feeling, rather than thinking.
"Malfoy tricked you," Hermione said to Harry. "You realize that, don't you? He was never going to meet you – Filch knew someone was going to be in the trophy room, Malfoy must have tipped him off." (9.169)
Malfoy, as a Slytherin, is supposed to be more adept at cunning than courage, and this moment only proves it. He didn't just chicken out of his midnight duel with Harry; he never planned to go at all. It wasn't meant to be a test of his courage, but a test of Harry's gullibility.
Harry then did something that was both very brave and very stupid: He took a great running leap and managed to fasten his arms around the troll's neck from behind. (10.123)
Here's where that idea of being "brave at heart" (7.33) kicks in again. Harry attacks the troll by being "both very brave and very stupid" – but that stupidity is almost necessary in order for him to be able to act bravely. If he'd stopped to think about it, he would have probably realized that jumping on a troll is not high on the list of acts of self-preservation.
"You've got to stand up to him, Neville!" said Ron. "He's used to walking all over people, but that's no reason to lie down in front of him and make it easier."
"There's no need to tell me I'm not brave enough to be in Gryffindor, Malfoy's already done that," Neville choked out. (13.28-29)
Ron's trying to encourage Neville, but Neville takes it as an insult. It's too bad, because Ron's right – they all have to "stand up" for themselves. Yet, that's easier said than done, especially for someone like Neville, who's frequently made fun of and shamed by the idea that he's "not brave enough."
"It's people they feel sorry for. See, there's Potter, who's got no parents, then there's the Weasleys, who've got no money – you should be on the team, Longbottom, you've got no brains."
Neville went bright red but turned in his seat to face Malfoy.
"I'm worth twelve of you, Malfoy," he stammered. (13.77-79)
Malfoy just doesn't stop with the insults, does he? We're guessing that, in this case, he's being so cruel because he's jealous: the Gryffindor Quidditch team is actually very good, and they really have assigned the best players to the field. Since their team is a match for Slytherin technique-wise, Malfoy tries to undercut them on a morale level. It takes a lot for Neville to reply to Malfoy here, even if it doesn't accomplish very much.
Harry caught Neville's eye and tried to tell him without words that this wasn't true, because Neville was looking stunned and hurt. Poor, blundering Neville – Harry knew what it must have cost him to try and find them in the dark, to warn them. (15.9)
Harry's right to feel sorry for Neville here; Neville's sacrificed himself on Harry and Hermione's account, and Harry can't even tell Neville the truth about what went down. So often when Neville tries to be brave, he gets in trouble himself: here, he gets detention.
"Don't you call me an idiot!" said Neville. "I don't think you should be breaking any more rules! And you were the one who told me to stand up to people!" (16.114)
Here Ron's encouragement to Neville backfires, as Neville takes his advice at precisely the wrong moment and stands up against precisely the wrong people. Yet, in some ways he's right to stand up for himself here, to demand that people don't call him names, and to encourage them to follow the rules. After all, he's seen firsthand the trouble they get into when they don't.
"If you want to go back, I won't blame you,' he said. 'You can take the cloak, I won't need it now."
"Don't be stupid," said Ron.
"We're coming," said Hermione. (16.148-50).
Once again bravery is act first, think later, as Harry tries to persuade his friends to turn around and let him go forward alone; as Ron tells him, that's "stupid." In a way, it is foolhardy of all of them to continue, as their bravery puts all their lives in danger. True, it's totally worth it in the end, when they defeat Voldemort and live to fight another day, but that doesn't mean it was smart.
'How touching…' it hissed. 'I always value bravery…. Yes, boy, your parents were brave…. I killed your father first, and he put up a courageous fight… but your mother needn't have died… she was trying to protect you…. Now give me the Stone, unless you want her to have died in vain.' (17.70)
Voldemort may "value bravery," but that doesn't mean everything he's saying here is true – he's using Harry's parents' bravery against him. He implies that Harry's mother will "have died in vain" unless Harry hands over the Stone. Of course, Harry takes this in the opposite sense and becomes even more determined to not give in: to act just as courageously as his parents did.
"There are all kinds of courage," said Dumbledore, smiling. "It takes a great deal of bravery to stand up to our enemies, but just as much to stand up to our friends. I therefore award ten points to Mr. Neville Longbottom." (17.197)
We're glad that Dumbledore's noticed Neville's bravery, just as we have. In fact, if you look back over the list of quotes in this section, you might be surprised at how many bring us back to Neville. See, Neville is brave, just as brave as anyone else in Gryffindor. Dumbledore reminds us that "all kinds of courage" exist in the world and Neville's been participating in an important one: "stand[ing] up to [his] friends." He's faced enemies, too, but sometimes it's just as difficult to face down your companions. Don't forget: it's these final ten points that Neville wins which give the Gryffindors a win at the house cup, too. Sometimes small acts of bravery are the most pivotal.