Another thing not very well justified in the writing is the idea of an eternal struggle between these two idiots. Since when have they been immortal? Aren't both simply humanoids who will grow old and die pretty soon (even if they have "the recuperative powers of a dinosaur", which they probably don't since McCoy didn't know about the switcharoo when giving his expert opinion), not to mention starve or succumb to thirst within a week already?
Timo Saloniemi
Well, time has no meaning there. The predator has no teeth. Ahem. What I mean to say is that if you're not properly in a universe, how does time pass? Answer? It won't. So they're stuck in the Void, if we're going to be all Doctor Who about it, and they won't age or die or any of that because without time you can't get any older can you?