[Ravager]

So, this man was connected to a demon in some way, though it was hard to tell whether it was for good or ill. If he was telling the truth, however it would mean he had no memory of any dealing with this demon other than having seen it. It's possible that a deal struck with the demon would have led to amnesia or it was an unwilling side effect of something else.
Or, it could be that he was attacked or captured and escaped. He considering using his innate abilities to detect whether this man was evil or not, the only possible problem was that he still didn't remember what happened before seeing the demon, but something had scared the clerics and it was unlikely to be good.
"An interesting quest, what do you remember from when you first awoke? Did you have any equipment and do you remember you were? That would make a good starting point.
I do have a requirement if you wish me to aid you though. I wish to check you for signs of evil. It isn't invasive and it wouldn't hurt. It would just put a couple of my concerns at rest.
As for my companions, it is of course their choice."