The Fallen (Monsterverse x Male Oc)

Before the existence of Titans was revealed to the world, three alpha Titans, Godzilla, Mothra, and Kong, but one Titan was born to throw the entire world off balance including the Hollow Earth. Ochita Raijin, a human that was blessed with the power of a Alpha Titan that not even the three couldn't control yet were friends with. Of course, he remained as a humanoid creature that blended in quite well with the human population. Years later he was sealed off due to the radiation in his body mutating him turning him into a beast that fell from the grasp of creation.