All Muir has ever known is a life of science (and evil, as some would point out). Raised by Dr. Diablerie and surrounded by members of the research-oriented villainous Consortium, Muir probably would have continued down his path if not for a fateful capture on Eclipse grounds.

Having been talked into staying on as a sort of experiment rather than simply going straight to jail, Muir doesn't really understand what it means to be good. However, the language of science and discovery is universal, and maybe he'll figure the rest out with time.

Though it's difficult to call him gentle or normal given everything he's been involved in as Caustic, Muir is surprisingly even-tempered and polite when not in costume. In costume, however, he certainly amps up the theatrics of being a minion—after all, he'd better not tarnish the mad doctor's reputation (cue ominous laughter)