"right!" Sans-Serif nods his immediate agreement, smiling in reassurance up at his brother. And now that Tauriel is here with them, it's an offer of reassurance that doesn't even look strained - he means it wholeheartedly. "it's not just us anymore, s-4. it's tauriel, too." Back when they had first discovered the idea of mothers, Sans-Serif had had his doubts about S-4's initial assumption that mothers and brothers were anything alike. Cats and hats weren't, after all. But now that he has one of his own, he can see that they're very similar, that a family can be more than just one person.

He looks to Tauriel, then, because Sans is bad at explaining things to anyone who's not another him. "we need to find his lab. this has happened before. i think he knew it could happen now. so if we find his lab, m..." He almost says "maybe", but stops himself. "...we can find a way to fix him!"