Ifrit

Ifrit is a deceased S class Demon who surpassed Satan in his prime. Ifrit is the son of Satan as well as the uncle of Jacob (Morningstar). After he died, Ifrit reincarnated into Jack Drake, who then laid dormant until Jack obtained Demonic magic. Not much is known about Ifrit himself but we do know that he was a very strong demon and can rival Cthulhu.