I keep thinking about that scene in 'Harry Potter and the Order of the Phoenix' where he trashes Dumbledore's office. Some authors just get that raw, ugly teenage rage so right, the kind that's been simmering for years. A fic that really stuck with me is 'The Sum of Their Parts' by holdmybeer. It's a postwar story where Harry, Ron, and Hermione become vigilantes. There's a moment where Harry just... breaks after seeing another pure-blood bigot walk free. It's not a tantrum; it's this cold, calculated, terrifying fury where he lays out exactly why the system is rotten. The anger feels earned, built from all the loss.
Another one is 'Stages of Hope' by kayly silverstorm. It's a dimension travel fic. Harry from a war-torn alternate universe arrives in a brighter one, and his anger is quieter, more internal, until it isn't. He snaps at their Dumbledore for being naive, and it's all the more powerful because it's delivered with this exhausted, shattered conviction. He's not yelling; he's stating facts, but every word is drenched in pent-up fury from watching his world burn.