Prince Thrommel

[Anon Emous]

Firstly I'm sorry if this has already been discussed, but upon searching the forums I could not find a post that gave an answer to my dilemma. Ok, here goes!
I have found the Prince tucked away in the secret room, and upon opening the door to said room there is a piece of dialogue from an NPC mentioning letting the vampire sleep. But as soon as you enter the room you can talk to the Prince normally. Even though he does mention an illusion placed upon him.
Now comes the problem. When I offer to lead him out of the Dungeon, he agrees but nothing happens. He follows me so far, but will not move up stairways. If I enter combat he attacks my party. If I Teleport out of the Dungeon, he does not come with me but is still stood where I left him.
So what do I do? If I release him he gives me a gold chain, but does not mention a reward. If I kill him I get Fragarach, but obviously will not get Scather. So I'm a bit stuck on where to go next.
I'm running the game with the official patch and the Co8 v2 patch, could one of these possibly be causing the problem?