777 is a bio-engineered clone created at the Dead Leaves lunar prison facility. He serves as a prison guard alongside his counterpart, 666. Physically, 777 possesses blue hair, blue skin, and an imposing, muscular frame. He functions as the physically stronger but less agile half of the guard duo. His body integrates weaponry systems, and he relies primarily on brute strength and internally stored firearms in combat.

Notably, 777 utters brief prayers before engaging in violent confrontations, a habit criticized by 666. During the uprising instigated by Retro and Pandy, he confronts inmates with extreme force. He impales and kills the prisoner Dick Drill after Drill's attack lodges in his neck. 777 also battles Retro directly, employing piercing attacks with his fingers capable of penetrating opponents.

777 meets his end when the cyborg warden Galactica absorbs him during her transformation into a giant caterpillar entity. He becomes part of the composite creature ultimately destroyed by Pandy and Retro's mutant offspring. The character's narrative function remains confined to his role within the prison system, with no depicted background, development, or appearances beyond these events.