Billy, [ he says immediately, relieved at the fairly relaxed response, and offers out his hand politely. ] William Kaplan-Altman, but I mean, everyone calls me Billy. I'm one of your grandsons. [ well.. technically. it's not quite that straightforward anymore, but getting into it seems like more work than necessary here.

and because that isn't the sort of thing you expect to hear every day, probably, billy nods his head back in the direction he came. ]

From an alternate reality, that is. You're, um.. older back home, but you're still pretty clearly you. [ he flicks the index finger of his other hand toward the sword, sending a little shower of blue sparks racing along the blade. ] Your mutation's pretty distinctive.