[The first few things that come to mind are immediately self-centered - "Come on, you know I'd never leave you behind" and "Hello, theoretical person, Dr. Alphys loves you! Too bad you're not real!" and the heavy slam of locked doors - but after a moment the rest clicks too; it's a combination of the fight a few days ago with Undyne and the phrasing this girl is using now, but it's not particularly deniable that saving humanity is leaving his own people to suffer, and damn, that's unpleasant, isn't it.

The, uh, buffering period is kind of obvious, but thankfully he's not a total mess when he collects himself; he smiles eventually, and again, he'll do her the courtesy of verifying that she isn't off, because that's only courteous - whether this is proper magic or an elaborate show, you tell the damn performer when they've done well if they have.]

Two for two so far - you're good at this.

But... No one knows the full story behind that, and I think I'm going to keep it that way for now. I'll verify that there are broken relationships and sacrifice involved all over, though. Moreso than just the average person's occasional broken bridges.