[As Sans talks, Papyrus turns to check down the hall again. The doppelganger's still down where it was flung, a little shifting, but the pieces seemingly not gathered enough to charge at them again. Yet.]

Further in sounds like, exactly the direction I don't want to go. [He's a little more vehemently earnest in that than anything else he's said this reunion, more than he meant to be. But his face doesn't twist in a grimace, his nostrils don't flare - it's mostly only in a flinch around his eyes and shoulders than give it away.]

Going back sounds fine. Even if... there's a mysterious opera theater, in a bomb shelter...? [He's not clear why there'd be a theater devoted to opera specifically, instead of just some kind of entertainment room for people to distract themselves from the bomb threat, but then he's not used to life in a world where shelters from bombs are needed. Coincidentally, he hazards a guess why Sans bothered to mention it:] I wonder if that's where the music was coming from...