Very little is known about Ditto. He is a process server for the prestigious Goodman, Lieber, Kurtzberg, & Holliway law firm, where his shapeshifting talents are invaluable. Even the most reluctant would-be witness is often tricked into signing Ditto's subpoenas by his ingenious impersonations. He has assumed the identities of Clint Eastwood, John Glenn, and can do a very good imitation of Orlando Bloom for the ladies.
From what little is seen of Ditto "himself", he seems to be very playful and mischievous when he is not serving papers. During Jen Walters' first day at work at Timely Plaza, Ditto introduced her to the staff of the law firm in the guise of senior partner Holden Holliway. He may have gotten into some sort of trouble with the law before working for GLK&H, since he once commented that he did not want to go back to jail. Like much of the staff of the superhuman law division of GLK&H, Ditto lived at the Excelsior Apartments and was both a roommate and friend to Awesome Andy. That friendship was ended after Ditto told Titania (after being threatened by her) that Jen Walters (She-Hulk) was likely back at work if she was not at the apartment complex. This led to Titania's attack at Timely Plaza where Mallory Book was crippled and Awesome Andy nearly lost his life. Ditto was able to help She-Hulk defeat Titania by tricking her into thinking she killed Jen, who was really Ditto in disguise. The Infinity Gems work only for those that bear extreme desire. Therefore, with Titania's desire apparently achieved, Jen was able to remove her gem and subdue her. Nevertheless, Andy broke off his friendship with Ditto, who has since left the firm and disappeared.
