In the ambreigns fandom we don’t say “I love you”, we say “Loser buys beers” and I think that’s beautiful.
The difference between Killian and a lot of other villains on the show is the fact that Killian is GENUINELY bothered by what he turned into. And rather than wallow around in it, he tries to put himself back together. Everyone is there telling him how horrible he is and a deep part of him agrees with them, but if it will help Emma, he'll defy his OWN perception of himself to make her happy. He still thinks he's too far gone, but he's willing to TRY.