Well, if it's any consolation, I can't find which quest I'm stuck on with my warlocks for the fel hunter. I think I did a quest or two while leveling them up and just didn't finish the line, then abandoning all quests when I picked up leveling them again.

I swear I've walked from quest giver to quest giver and none of them seem particularly interested in talking to me.

So yes, I have 4 level 80 warlocks and no fel hunters.