Marcel was one of the mice that was turned into a human when the fairy godmother used her magic to prepare Cinderella for the ball. Instead of waiting by the coach like the other mice-turned-men, Marcel snuck into the ball and, when the clock struck midnight, he was allowed to remain a human due to a loophole in the spell. He spent his human life mating with as many women as he could find, often producing human/mouse hybrid children as a result.
At the end of the Of Men and Mice storyline, Marcel was returned to mouse form and blinded in the process. He is now part of the Three Blind Mice.