Kayn and Rhaast are actually considered one character; however, they're a human-demon hybrid named Kayn and Rhaast. To be specific, Kayn is a shadow assassin who wields a scythe possessed by a Darkin.

Kayn’s scythe, Rhaast, is one of those demon-people. Kayn wields an ancient weapon and fights the darkin within it, Rhaast, for control. During each game, one will consume the other. Kayn hones ...