A former sailor and captain, Mortimer was among those who retired to the Sandy Coves Convalescent Home. He was among the many there to experience his age; bound to a wheelchair and experiencing dementia, he (like the others dwelling there) would occasionally lose their safe key. Prompting their caregivers to program the Mister Handy robots to remember where they habitually hide it. In his case, in his favorite ship model. His dementia was quite severe; missing the sea, he filled his bathtub with fish and mock fished for them.
His room is littered with sailing paraphernalia, model ships fill the shelves and ship paintings hang on the walls. Beneath his window, next to the radiator, is his life ring, propped up against the wall. On his dresser, next to the swan boat model, is a bottle of bourbon and his shot glass. In the corner between the dresser and the wall is his biometric scanner. Above his bed lies his board, and on his nightstand lies his captain's hat and lantern.
Mortimer is mentioned only in Fallout 4.