Caliban was a weak and submissive mutant after he was bullied by various factions, eventually he gave himself over to Apocalypse to be genetically altered to become stronger, more dominant. He moved in and out of the control of Apocalypse and eventually, Caliban digressed to a more primal nature before finally regaining his faculties. He would eventually die by sacrificing himself for a friend, only to be reanimated for evil purposes.
After an initial confrontation of Morlocks' with the X-Men, Storm became their leader and a tenuous association was made between two teams. Caliban's powers were used to locate and kidnap their newest member, Kitty Pryde. Callisto wanted a second confrontation of X-Men in order to take back leadership of the Morlocks from Storm, and Kitty was the bait. Shadowcat was then to be kept as a Morlock, married to Caliban, but the plan was failed when he realized that Kitty would never be in love with Caliban and that she belonged on the surface with the X-Men.
In M.U.G.E.N, Caliban has been made once by Blagoy & Acey.
This version of Caliban uses custom sprites seemingly edited from Zangief, and gameplay wise, it's typical of Acey's creations with AvX code. However, he does have a few oddities that set him apart from other characters, such as an attack which allows him to adjust the position of his opponent freely, either bringing them closer or father to him, or even upwards and downwards if the player wants to do so. This attack, known as "Fear" in the character's files, does little damage by itself, but allows Caliban to start combos almost effortlessly or easily use supers/hypers on helpless opponents. This is upped to a ridiculous level of efficiency against most AI, as numerous opponents will not be able to understand what is happening when they are under the effects of being moved by the attack, making him a bit cheap.
His AI is typical of Acey's work, being of a fairly skilled level, but still being easy to defeat with a proper strategy. It rarely uses Fear, and does so in a manner not nearly as efficient as the player can.