Seth does notice the flinch, being as focused on Daniel as he is, and immediately feels guilty. He doesn't really want to punish Daniel for what happened, what was completely out of his control. Part of him might be wanting to punish Daniel for killing those people, but that's not fair either. It's not his place, it won't do any good, and it probably isn't really deserved. It's just... difficult to be confronted with, when he was perfectly content to leave it to his imagination, or just not really consider it much at all preferably.

"I dunno, you were the one who suggested talkin'," he answers, though sounding a fair bit milder now, intentionally so. He can't hide how weary he feels though.