So how far would this rivalry go? Is the mutually assured destruction thing important? Does she actually [i]want[/i] to destroy him? I don't think he'd want to destroy her, he'd just think of her as an annoying littler sister who he doesn't understand. Though just to annoy her he'd totally turn felines against her. XD

As for the Norse Pantheon, most of them are pretty alright I think, not like the Greeks who rape, murder, and curse literally everything. It'd be war though... So surely the gods would band together against their rebelling offspring, meaning the Norse too? Some are bound to die in battle, but those who survive- who's pride isn't the size of Yggdrasil anyway, would probably swear the oath and live. Which begs the question; which side were you on in the war?