Reading 'The 100' fic is practically a masterclass in forcing characters to look into a mirror they’ve been avoiding. You see it most with Bellamy, post-Season 3, or even with someone like Murphy. The writers don't just have them apologize and move on—they build the damn mirror from scratch.
A lot of authors use the Grounder perspective, having a character live among them after committing an atrocity. It's not narrated guilt; it's shown through daily discomfort, learning a language they mocked, surviving a ritual they once called barbaric. The redemption is earned in the quiet moments: Bellamy teaching a Grounder child to read, or Clarke having to ask for forgiveness in Trigedasleng, stumbling over the words.
My favorite trick is when they pair the 'redeeming' character with someone who canonically died, like Lincoln or Lexa, in flashbacks or dream sequences. It's not cheap nostalgia; it's the ghost holding them accountable, forcing a conversation they never got to have. The arc finishes not when the character feels better, but when the community they harmed starts to tentatively trust their hands again.