Beelzebub

Once upon a time, in the kingdom of heaven, there was a god named Beelzebub, the lord of the flies, who was cursed by the king of hell, Satan. Because of his curse, no god would approach him, since anyone who did died losing their heart, and Satan devoured them.

In the past, after meeting Lucifer, Azazel, and Samael, Beelzebub quickly developed a strong bond and close friendship with them, beginning to feel happy and grateful to no longer be alone. However, due to his curse, he found his three friends dead and with their hearts ripped out.

From then on, his sole goal was to find and kill Satan with the help of Lilith, but once again, when he began to develop affection for her, he was eventually killed. This led him to learn the brutal truth that he is actually Satan.

After all these events, Beelzebub lost his will to live, becoming somber and introverted, forbidding himself from bonding with anyone, creating an emotional armor to keep himself safe from other people and avoid suffering more than he's already endured in his life. His only desire is to find someone who can kill him.

After Papiyas's mysterious disappearance centuries ago, Beelzebub began collecting small samples of the demon, as he had left behind remnants of himself after destroying half of Helheim. Once Beelzebub collected the samples, he returned to his laboratory to experiment with them, eventually cultivating them to create a "seed" that he would implant in Zerofuku.

Beelzebub appears as a young man with short, messy black hair and slightly elongated, pointed ears. He wears a black cassock with buttons at the collar that display a pattern resembling the compound eyes of a fly. Beelzebub also wears a long, purple stole with black stripes similar to a tallit, and black combat boots.

Beelzebub has proven to be quite calm, as he wasn't too surprised by Zerofuku's transformation. He has a fondness for gathering information and experimenting, as his private room featured shelves of books, several jars containing preserved specimens, and a table containing various surgical and mechanical tools. Beelzebub doesn't appear to have any interest or concern for others, as seen when he implanted Papiyas's "seed" into Zerofuku, showing indifference to what might happen to him and even feeling a certain pride when he saw that the demon managed to emerge within Zerofuku's body. This lack of empathy stems from his own guilt at having murdered his loved ones, turning him into a cold being unable to form any kind of bond with his fellow human beings.

Despite his coldness, Beelzebub has shown to have a certain respect and appreciation for Hades, who for a long time was his only emotional support and the closest thing to a friend, to the point of fighting in the eighth round of Ragnarök to avenge his death.