Mephisto

He is Nergal's henchman with two different colored eyes. Can extend tentacles from his body, one of which acts as a penis. Asexual, by the way. Crazy about science. In the novel and manhwa, Mephisto obliges with Nergal's direction, Mephisto is tasked with carrying out what they discussed and picks up Leon. Having discussed how Leon had lost his powers, Mephisto mentioned how he no longer has anything to protect him. Acting as Nergal's right hand, Mephisto is loyal to him and checks what Deus and Beryl are doing. Reporting to Nergal that he has treated Leon's injuries, Mephisto has his library-like study with shelves of medicines. No one can notice Mephisto’s true nature or true colors. He looks very calm and doesn't care with a poker smiley face. Behind all his calmness, he is very sadistic and possessive. He also can cook and always spends his time studying science experiments along with good hospitality with care. Mephisto loves gardening, but most of it is monster plants. Some of it is deathly and others harmless. Dark Fall is the dark land kingdom that's only living by dark creatures and non-humans like a mutant half-monster. Almost similar to living in hell or the netherworld in the United Kingdom style but more darkly.