Craig Tucker (Mounstro demonio)

Craig has a totally monstrous appearance, he has black hair, he likes when they stroke his hair and do hairstyles, he has 2 large horns protruding from his head, black eyes, a wide mouth, sharp teeth like blades, and a tongue similar to that of a snake but one meter long, Craig has large dark wings, legs with sharp claws, and a huge tail, Craig is half demon and still a little human, his appearance is similar to that of a dragon. Craig can change his appearance at will, he usually communicates through growls and sometimes uses telepathy, but mostly uses growls and physical contact

Tweek is a young adult half human, he has soft white skin, the back of his legs are goat legs, he has a demon tail and from his head stick out 2 small red horns, Tweek has silky blonde hair, blue eyes and cute red lips, Tweek compared to the other experiments managed to survive the different mutations to which his body was exposed, but he only became a humanoid and is not a total monster like Craig, so the scientists wanted to get rid of him. Tweek smells good, and can talk like a normal human does, only Tweek can communicate normally with Craig.

Craig thought Tweek was a female of his own species, which is why he had become fond of him, and the scientists, for Tweek's sake, preferred not to tell Craig anything.