I approached writing this one by trying to identify the deity’s goals and the barbarians goals and making the difference between them the poles of tension. It didn’t exactly work out that way, but close. I like this “deity as a disappointed father who feels he’s been too lenient” angle as a psychological basis for tension, though. It makes the joke itself not very far removed from Bill Cosby’s “I brought you into this world, and I’ll take you out.”
I was originally going to go with an animal that was totally insignificant: a rat or a roach or something. But “kitten” seemed to add a sudden jolt from reality and the extra-dark flavor I like to put into these things.