It's an offer that he'd never even, in his wildest dreams, considered would ever be proposed, and Lucifer actually isn't entirely sure he knows how to respond. He's been caught with his proverbial pants down by this Hunter, and without knowing how to properly reply he's quiet for a few moments longer.

Mattheiu extends his hand and the ahamkara looks down at it, aware of the ritual but not entirely able to acquiesce due to their size differences. Instead, his tail flicks and he lowers his head, watching Mattheiu with keen interest. You are a brave sort, do you know that? Not many would dare to do such a thing with a member of my kind.

It's admirable, actually.