What is IT?

Fiancé: “What is IT, anyway? Like, what’s he supposed to be?”

Me: “An alien.”

Fiancé (sounding, to my ear, unconvinced): “Ohhh.”

Me: “He came down to Earth from space.”

Fiancé: “REALLY, Carrington? Is that what aliens do?”

Me: “I wasn’t explaining what aliens are; I was justifying my position with evidence from the book!”