Seth snorts softly at the question. He has a million things to be sorry for, though he's not sure if he can articulate all of them, or how many are relevant to this conversation.

"For... I dunno. Not being as good as you think I am?" he suggests. That's definitely a significant one. Feeling like he comes up short. And not just in achievements or talents or quantifiable things, or even a basic ability to function. But basic morality, compassion, forgiveness, patience, openness.

Daniel's probably right in not wanting to descend to basic humanity again. Certainly not for Seth's sake, and Seth is foolish and selfish for even wanting it. For being upset about it, and letting Daniel see it. Forcing him to deal with it, because of course Daniel would.