[So they have...parents from other species? Do all monsters adopt troll kids on his planet? That's sort of a weird custom, but if it works for them then Frisk won't judge.]

Uh-huh! She adopted me. Or, um, she's tryin' to. There's a lotta papers an' meetings an' stuff.

[Of course, as far as Frisk is concerned the legal stuff is meaningless. They're a family, and that's what matters.]

She's not here right now, though.