It is a glitchy, no speaking rampaging, flooding ink-like liquid blob of darkness with ear-piercing glitch noises that assimilates everything in its path and whose origin is unknown. All that is known about it is that it’s a mindless force that seemingly targets cartoons and turns all characters it assimilates into mindless agents that it uses to spread its influence. It is a glitchy, rampaging, flooding ink-like liquid blob of darkness with ear-piercing glitch noises that assimilates everything in its path and whose origin is unknown. All that is known about it is that it’s a mindless force that seemingly targets cartoons and turns all characters it assimilates into mindless agents that it uses to spread its influence. Anyone absorbed by the Darkness becomes its puppet to spread it as well as amplifying their worst traits.

Pibby is the titular main protagonist of Learning with Pibby and Learning with Pibby: Apocalypse as the main character of a toddlers' entertainment show, she teaches lessons for children with her best friend Bun Bun, and likes hugs and having fun. although Pibby is depicted as sweet and innocent at the start of the series, not even knowing what blood is due to the sheltered world from which she originates, she is forced to become a hardened warrior over the course of the series, battling an unknown, dark entity that has corrupted the other cartoons. Pibby is a small, light-blue colored preteenager with lilac colored hair.

Bun Bun is the deuteragonist of Learning with Pibby and the secondary antagonist of Learning With Pibby: Apocalypse. He is Pibby's best friend amongst the other animal creatures she befriended until the Darkness arrived. Bun Bun appears like any normal white-haired rabbit, having a slightly pink-tinted nose and large pink ear holes. He has one tooth sticking out, stubs for his limbs, and a circular tail. Following the bondage with the Darkness, Bun Bun transformed into a giant blob of distorted gloom.