A substance from the TimeSplitter found in the Biohazard Container was used to try to turn them into superhuman beings, but instead mutated them into the hybrid they are, with features of the Reaper Splitter evident. A similar thing occurred with the Freaks, which is why they have a resemblance. They too are half human and half TimeSplitter, but their Splitter half resembles the Berserker Splitter as the Freak was an early attempt by Crow at creating a Berserker Splitter. Also, the freak is capable of shooting bolts of lightning, whereas the Hybrid Mutant cannot and simply acts like a zombie.