Oh, you must use "werewolves mate for life"! I was just recently reminded that a werewolf was also the first monster Ten called beautiful. (The werewolf, the automatons from Girl in the Fireplace, and I think he also gets complimentary about the werewasp from "Unicorn and the Wasp". And the Master, of course!)

But how about the oldest fanfic cliché of all, courtesy of Star Trek - sex or death? Any plans for good old pon farr?