Blo is a parasite that looks like a slime.

Due to its appearance, no one suspects it is a parasite. It enters its victims' bodies through their mouths and lodges in the brain, where it can manipulate them. When it does so, it causes a green glow around their pupils and instills an almost insatiable hunger, making them believe they are acting of their own volition. When its victim eats to the point of immobility, Blo leaves the body. Sometimes, upon leaving, it can cause memory loss, essentially forgetting what they did while under its control. Furthermore, it can travel between dimensions and universes (when it travels to another dimension or universe, it does so randomly).

Art made by 525252

Victim without memory loss:
https://www.furaffinity.net/view/62816478/

Victim with memory loss:
https://www.furaffinity.net/view/63245714/