This is a "nice" guy
Coming from an ancient bloodline, Xyllon can trace his origins to both fey and dragon. At a young age he showed a proficiency for magic, and he began working towards becoming a skilled sorcerer. He appeared to be on track for a good life, when everything changed. At the age of 18 an unknown enemy attacked his village, reportedly slaughtering everyone but him. It is speculated that the only reason he survived was the reason he is now a wanderer, forever alone, excepting an occasional adventure with some sympathetic adventurers. It is hypothesized that during that fight he saw his family slaughtered, leading to a mental break of some sort. This allowed him to cast magic far stronger than he ever did, but that break never healed. It certainly didn’t help that he died early in our adventure, and was somehow resurrected shortly after. To this day I do not know what happened to revive him, or what happened to the jade frog that he awoke with.
None of his history prior to his adventure with me is known for sure, however, as Xyllon never spoke of this with me, or anyone else who has known his company. All that is known now is that he appears to frequently have conversations with a devil and an angel, both of whom appear to dictate his actions. It appears he listens to whichever one suits him at the time, leading to unpredictable behavior. I am a prime example of that. During an expedition into what turned out to be a tomb, Xyllon suffered a break after immolating several guards. He turned on me, and that was the closest I have ever come to death.
Later he muttered something about skeletons consuming us, so to the best of my knowledge he was acting to save us, but he is still dangerous. Any adventurers who accept him or who he latches onto, be warned, you will never be able to predict what he will do. His goals are his own, and no one knows what those are.
-The Lone Wanderer, by Yendor the Bard