History
Kaine summoned Zarathos in an attempt to save the life of his nephew, Reilly Tyne (the son of Ben Reilly and Elizabeth Tyne) who was dying because he had inherited the genetic defects from his father's cloned physiology. This backfired when Zarathos attempted to claim Tyne's body as his own. At the same time, Kaine also tried to bring Daredevil (who had been killed by the Kingpin while saving Kaine's life) back to life. The soul of Daredevil took up residence in Tyne's body. The forces of the two spirits residing within him tended to keep each other in check, Tyne gained Zarathos' physical appearance, demonic and regenerative powers, while the influence of Murdock kept him from becoming corrupted. Under the influence of these two entities residing within him, Tyne decided to become the hero Darkdevil.