User blog comment:Neowitch/680 - "Two men walk into a lab..." Stop me if you know that one!/@comment-1595565-20120905145107/@comment-4493594-20120905170550

Nah, I'm pretty sure the "nice guy" is just some sort of disguise.

As for the sister thing, it's probably the best excuse he could come up with if he ever got summoned by Joker to go somewhere.