Fred was first seen in September 1998, where he confirms that Bianca Butcher is expecting a baby. He is the permanent replacement for Doctor Harold Legg, who retired as Walford's GP in 1997. Fred moves into the flat above the surgery with Mick McFarlane. Unlike his predecessor, Fred is not always willing to listen to the medical complaints of his patients outside office hours and is accused of being vulgar and insensitive at times. That, as well as his holistic, non-traditional approach to medicine, does not endear him to all of his patients initially. Fred comes from a wealthy family; his father is a consultant. It unravelled that Fred had not wanted to pursue medicine as a career, but family pressure forced him into the profession.
Fred and Mick become good friends, but despite their closeness, Fred feels unable to tell Mick that he is gay. When Fred attends a medical convention in Brighton in the summer of 1999, Mick and several other residents of Walford go along too. While on the trip, it becomes apparent to everyone, bar Mick, that Fred has something he wants to get off his chest. Fred decides to take Mick to a gay club in the hope that he might guess his sexual orientation, but Mick remains blithely ignorant and is extremely shocked when Fred finally confesses. Mick does not care that Fred is gay, but felt hurt that Fred had not confided in him sooner, and is just as perturbed to discover that Fred doesn't fancy him. Their friendship remains intact, although Mick's mother Josie who is also Fred's receptionist, is not so understanding and denounces Fred's lifestyle as immoral.
Fred's sexuality also brings to the fore homophobic tendencies in other residents of Walford, including teenager Martin Fowler. When Josie's confused stepdaughter, Kim, approaches Fred to find out more about homosexuality, Josie accuses Fred of "recruiting Kim to the gay cause", and states that he should not be around young children, which profoundly offends Fred. Shortly after, Dr Fonseca decides to leave Walford to work in a new practice in Islington in February 2000.