[Ren pokes his tongue out a bit as his nose is tapped, but plays along with it all the same. He's mostly just being silly about it, honestly.]

Everyone's fingerprint has a different pattern. So you need a machine to tell all the differences, but they're pretty common in my world. It works kind of like those chests in the temple, the ones that don't open unless it's you trying to open them.

[Except it's technology instead of magic, but it's the best comparison Ren can think of that's not just going to be incredibly confusing.]