Supreme Beings Edit
Cocytus considers himself the 'sword' of Ainz Ooal Gown, an object that does as he is told without ever questioning his master. When Demiurge brought up that they could serve Ainz's possible future heir, he got excited and hoped that he gets to be called 'uncle'. Also, when Ainz sent a Death Knight to ask the guardians what they wanted Cocytus asked that Ainz produce an heir and hoped to teach the "young master" swordsmanship, but due to Ainz being a magic caster he thought that the heir will an outstanding magic caster so he settled for protecting the "young master" and even daydreamed about it. Cocytus also greatly feared that Ainz would abandon them due to him disappointing him with his failure in conquering the Lizardmen and was greatly relieved after learning that Ainz did not blame nor was he angry at him.
Warrior Takemikazuchi is Cocytus's creator and previous wielder of the God Slaying Emperor Blade. Cocytus holds this blade to be one of his prized possessions so as to keep the memory of his creator close. Cocytus also shares his creator's knack in creating suitable names.
Floor Guardians Edit
Due to Cocytus' simple-minded thinking, Cocytus became the second guardian to fail a direct order from Ainz, this resulted in a brief scolding by Albedo. Other than that, they are shown to be on good terms with each other.
Cocytus is one of Shalltear's colleagues. Like her, he has experienced the taste of failure, so both share the same urge of redeeming themselves in front of Ainz.
As a fellow Floor Guardian, Demiurge is a colleague and at the same time a rival. Despite their rivalry for Ainz's attention and praise, they have a stable work-relationship. They are civil to one another to be considered drinking partners at Sous-chef's bar on the 9th Floor of Nazarick. He respects Demiurge's intelligence and confides in him on deciphering Ainz's plans.
Aura is Cocytus's colleague. Cocytus doesn't like it when Aura says that he's nude because it makes him sound like a pervert.
Mare is Cocytus's colleague.
Victim is Cocytus's colleague. They do not see each other often. Despite this, they maintain a cordial and respectful relationship.
Area Guardians Edit
Cocytus is on good terms with Kyouhukou.
Cocytus is on good terms with Gashokukochuuou.
Sebas is Cocytus's colleague and one other of the few good alignment NPC of Nazarick. Although he was ready to fight and kill Sebas if he were to be revealed as a traitor, he doesn't show any ill intention against the butler after his innocence was determined. It's unknown if the two of them share the friendship and rivalry of their creators.
Cocytus is a superior of Yuri and the two are not seen interacting.
Cocytus is a superior of Lupusregina and the two are not seen interacting.
Cocytus and Narberal are close to each other and get along unexpectedly well due to their creators being close friends.
Cocytus is a superior to CZ2I28 and the two are not seen interacting.
Cocytus is a superior to Solution and the two are not seen interacting.
Entoma was sent by Ainz to accompany and observe Cocytus in the war against the lizardmen. Cocytus tried to read her expression, but gave up since her face is just a mask used to hide her true identity. He even remembered the words of his friend, Kyouhukou, that Entoma is the scariest one of the Familiar Eaters.
For a short time, Iguva=41 was Cocytus's subordinate. Despite being under him, Cocytus felt guilty of losing him in battle to the lizardmen, since he was a personal creation of Ainz Ooal Gown.
Cocytus respects Zaryusu for his fighting spirit and ingenuity in combat. Cocytus petitioned Ainz Ooal Gown to resurrect Zaryusu as he believed it would be a pity to condemn such an admirable warrior to oblivion. He is currently overseeing Zaryusu's training and is always on the lookout to provide better equipment for him and all of the lizardmen that are under his care.
After the conquest of the Great Lake, Zenberu became Cocytus' subordinate. They have a good relationship though Cocytus is dismayed at the lack of proper manners Zenberu displays when talking to his master, Ainz Ooal Gown. He would have killed him on the spot for his insolence had it not been for Ainz's intervention.
Cocytus is one of Sous-chef's regulars at the bar.