@ Tempest: Yes, it would be a stretch, but so was the idea of a Sarevok Romance Mod. And while I am no Aeryn (in Baldur's Gate writing), that does not mean that it is not possible to make this believable and good. And did Xzar, if you bring him along in BG1, not die by Irenicus' hand and he's still alive and kicking in Amn? Edwin? Baldur's Gate characters have a habit of coming back to life (not unlike Dragon Ball Z characters). Why not Sarevok? And isn't trying to figure out a way to make it somewhat plausible not half the fun of modding?
@Nightwoe: I love your ideas! Maybe do the first idea where Sarevok is deemed useless by Irenicus and decides along the way that joining the PC after they escape the dungeon would be a good idea. Just a thought!!