Yeah, they'd definitely have some kinship there!

And with regards to rudeness, Kahl becomes friends with somebody who literally calls him a "vat rat" the first time she sees him. So everything up to and including really vicious racism isn't enough to put him off. However, he does straighten people out when they've been a jerk to him, it just might wait until he has enough time to think through what he wants to say.

So, things are open to however you'd like it to go!