Cool topic! I always wanted to play the games but didn't get around to it, so I don't have many specific ideas. What I've read is that the overarching plot got a little too complicated by time travel and resulting retcons, but changing one's fate is an important theme. Maybe it could have just happened one time in the series?
Though Raziel started out in an unrelated game called Shifter, I would keep him in the Legacy of Kain-verse as a good foil to Kain.