Having just finished re-reading this series for the umpteenth time, I must say that the character of Warin is raising some new questions for me. One thing which I have noticed is the similarity between Warin's followers and the Willimites in the Legends of Camber trilogy, who later became Revan's baptizer cult. That said, it was Morgan's comment about Warin having a "flair for intrigue" that really caught my attention. I know this might be a bit of a stretch, but could he have some familial ties to either Revan or that Willimite group of his? I know that Revan died in 922 with Javan et al., but if a remanant of that group survived then it almost stands to reason that stories of Revan and his matrydom would have been handed down through the group.
Another possibility, which also seems to be a bit of a stretch, is what if Warin was deliberately placed by a group of Deryni not from Gwynnedd, be they Anvillers or some other group from farther to the East? Perhaps he was covertly given the task of reminding people of some of the good which came from Deryni powers, namely: Healers. To this end, it would make sense for him to have been sent by the Anvillers, especially if they had harboured any healers who fled from the persecutions. This would mean that they would also have to have knowledge of how to block Deryni talents and/or suppress memories. After being blocked, it would have been a simple process to reintroduce a later generation back to the land where they once dwelt giving further credibility to the Willimite movement. A few generations later, Warin is born and eventually begins to show his ability to heal. With his family line having been blocked, he would have no knowledge of his Deryni heritage, or the extent of his powers. Also, he would pass as human to any Deryni unless that individual knew what to look for. Such knowledge now may only be known by the inner circle of the CC, ignored as there have been no known Healers until now.
Of course, it could also be coincidence, as this series was written prior to the Legends of Camber