In "The One With The Monkey", Ross shows up to Monica's New Years Eve party with Marcel as his date. On one occasion in "The One Where The Monkey Gets Away", Rachel has to look after Marcel and while watching a soap together he runs off. She quickly reports him missing, much to the fury of Ross, as Marcel is an illegal exotic animal. The group sets out to find the monkey before the authorities do. The woman searching for him turns out to be a classmate of Rachel and Monica, but they didn't treat her too well. Phoebe then finds Marcel, at the same time as the woman. Pheobe jumps in the line of the tranquillizer dart which is aimed at Marcel. Rachel then uses this as blackmail to allow Marcel free.
Zoo & film careerEdit
After staying at the zoo for some some months, there was a break-in and Marcel was taken (along with a snowy egret, a two-toed sloth, and three hooded sweatshirts from the zoo gift shop). He went into a film career, appearing in a Monkeyshine Beer commercial and then in a movie with Jean-Claude Van Damme. When Rachel asks how big of a star Marcel is, a movie crewman tells her "in human terms? I'd say Cybill Shepherd."
When Ross goes to the San Diego Zoo to see Marcel, the zoo administrator, Dean Lipson tells him that Marcel has died, however a rogue employee tells him the truth and that the story told to Ross is a big cover up because the zoo wants to avoid bad publicity. He tells Ross that the cover-up goes very high up, but is shocked to learn that Lipson knows.
While Marcel is filming Outbreak 2: The Virus Takes Manhattan, Ross tracks him down and spends a final day with him.