Just to contribute to this topic, this was pretty weird. I tried to talk to him and he always teleported away (I didn't find him a second time, maybe I just had explored the other places before and couldn't be arsed to look around for him again. Actually, I just thought he really disappeared completely).
Since he always returned to the first spot when reentering the place, I decided to attack him first and ask him later. He didn't teleport away and didn't ever retaliate. He just stood there. Blue tinted friendly npc. Taking hits. After about 30 hits confirming that I wanted to hit him ([a] [a] [enter]) he died and I could complete the quest. I feel like I cheesed it, and it was awkward when Leith-of-all-trades said he wanted to write a song about my adventure. Yeah, great song, maybe an instrumental one would fit.
I didn't get the xp from defeating him, but I got from the quest. I'm really not too worried about xp in this game, though. Like stated before in you guys' posts lots of monsters respawn in this game.