Wow I played through the game several times, never having an issue with completing his questline fully and easily. I thought I knew all the do and do nots, but I never knew about the "defeating any four bosses without giving him a scroll" thing. I have heard of many people complaining about the ways they messed up this quest, but never heard a whisper about there being a boss count tied to his quest. You guys really did your research when it comes to what can and cannot break an NPC questline. So basically, on NG++, i recruit him, then decide to play through the DLC bosses, come back and just do the deacons boss and he is out. That boy done gone forever yo.