Eaten by a dragon...or dragged to the depths by a mermaid as her unwilling husband...or he gets into the realms of the gods and in true Artemis fashion, turn him into a swine and he is hunted by the commoners he looked down upon and never helped. Just some out of the box suggestions.
I hope Raphael hurries up and finds Rowean. As for her father, I hope he has a lonely death, knowing he will never reach his goal of becoming immortal. I also hope it's death by heart attack. I say this because, I'm sure he broke Rowean's Mothers heart as well as hers!