*Sirius has just been arrested for murdering Peter*
Everyone who knew Sirius on the Dark Side: Ah, so Peter was the traitor. This makes perfect sense, Sirius is absolutely capable of murder when it comes to the Potters
*Peter rocks up in GOF alive*
Everyone, their brains doing a record scratch: Wait, what? Sirius didn’t murder him?
Peter literally never lives it down that he’s alive only because of Harry Potter, everyone brings up that the only reason Sirius didn’t murder him was because Harry told him not to and Sirius just didn’t have the heart to break it to Harry that James and Lily would be totally fine with Sirius killing Peter (the Death Eaters choked when it came out that Harry said he didn’t think his father would want his best friends to become killers, because that line was crossed during the First War and Potter never had an issue with Sirius’s dubious grasp of morality)
also!! all of them remember james fully fucking shit up with the most vicious curses that one time sirius was harmed and they’ve never underestimated the usual happy-go-lucky james potter once since then.