Rin Okumura is a seemingly ordinary boy living at the Southern Cross Boys' Monastery. One day, however, Rin encounters a boy who has been possessed by a demon. Amidst the struggle, he not only awakens latent powers sealed within him, but also learns that he is the son of Satan! No longer able to stay under the protection of the church and with his very existence straddling the line between human and demon, Rin decides to fight against his parentage and joins the True Cross Order as an exorcist. Now, the teen must attend the True Cross Academy and begin special exorcist training alongside his new comrades all while keeping his identity a secret; but can the son of Satan really become a true exorcist?
The setting and feel of the two series are vastly different, but both have two brothers fighting demons and supernatural powers. The main villians in both series is Satan (Lucifer). Also, one of the brothers in both series shares a similar fate.
Ao no Exorcist is mainstream shounen, while Supernatural is definitely seinen. However, if you like one, you'll like the other.
If you enjoy brothers fighting against demons look no further than these 2 titles. Plenty of action, drama, and hearache to be found in both. Supernatural is aimed at an older audience but I'm sure you'll appreciate one if you enjoyed the other.
Once upon a time, two brothers passed the happy days of their childhood by studying alchemy, which is governed by the equal transfer principle: an eye for an eye -- you can't get more than you give. But these brothers tried to defy that law, and a horrific accident resulted. Now, the older brother, Edward, is called the Full Metal Alchemist because of his metal limbs, and the younger, Alphonse, is a soul without a body, trapped within the confines of an automaton. Together they search for the power to restore themselves, to find the lives they lost so long ago...
Both shows are about two brothers on a mission (one to find a way to get their bodies back to normal, the other to find their dad and hunt monsters along the way). Both focus on the bonds between the two brothers with plenty of action and intrigue along the way. Although, honestly, the Supernatural anime doesn't to the live action justice, it's stilll an entertaining enough watch.
STN is a secret organization charged with capturing witches of all ages who misuse their inate ability of the Craft. Its newest recruit is a young girl named Robin, who wields the same power that she is helping to control. While skillful at their ability to detain quickly, the number of witches keeps seeming to increase, and the misuse of power grows stronger, casting a shadow of doubt as to what is really going on. For STN, there is much work ahead, and for Robin, her troubles are just beginning...
Both are based on a similar premise. A group of hunters going after threats to normal society. But where Supernatural goes after a smorgasbord of beings, in Witch Hunter Robin they are focused on one thing (what they call Craft Users). A great storyline. Enjoy!