[Sans realizes he said Frisk's name at the same time as he's trying to decipher Papyrus's reaction. It's obvious enough Papyrus is uncomfortable, and there's a million reasons for that in this conversation, but usually Papyrus is more dramatic about his feelings. Of course, he could be deliberately holding back on that for Sans's sake. Still, Sans feels some obligation to offer some defense for Frisk, because--]

I like the kid. I mean, it ain't like I remember 'em doing anything wrong. Maybe they didn't at all, I dunno. And they played along with my--confirmation, I guess. That they could travel through time. [Sans knew from Frisk's reactions alone, but there was something gratifying about Frisk going along with Sans's stupid passwords, even if Sans could only remember actually going through the last bit of it.] Couldn't've been them the whole time, but it's only one--one anomaly at a time.

[Sans had suspicions but no proof when it came to rogue talking flowers. And if Frisk has the power now, then Frisk has to remain the focus, rather than whatever it was before. Even if, by time and volume, the previous anomaly was more responsible for Sans's current attitude than Frisk.]