Don't think so... I'm not sure, but I think stocking companions with potions keeps them from permanently dying. That or they use them in battle, because they keep disappearing...
Yeah, I'm going to send Faendal home because I just like him too much for him to die. I think using resurrect on the console should restore her to normal, I'm pretty sure it did that in Morrowind.
Don't judge me on Faendal, I kind of gave him his own personality that I like.