Ayashi no Ceres, X Recommendations
Two close high school students become enemies due to their destined incarnations as opposing divine beings. Angels, legends, bloody violence and tragic romance. Overall, a very similar dark supernatural shoujo (e.g. bishounen) theme. Highly recommended.
Both series contain similar art style of the old school as well the darker mood, background, and tone of the story.
As of course with the story, there is the theme of predestination, saving/protecting loved ones, and obtaining one's identity in both anime(s)
There is a lot of drama, plot holes, twists, action, supernatural themes and dark background to go along wit the mix. Of course, with that...there is also tragedy and sadness in both series.
Both series also explores the theme of human relations through the interactions of other characters ranging from sibling, guardian, to couples.