William Merriman is the younger brother of Felicity Merriman. William is not quite three at the start of Felicity's series; he is three by the start of Happy Birthday, Felicity, implying a early quarter birthday sometime before March. He is an active little boy who likes playing in the mud, getting into mischief, and making messes. He enjoys following Felicity around and mimicking her actions. William is shown often in either shifts or breeched pants. However as a child who is never older than three, he would have not worn breeches as he was not sufficiently toilet trained yet and breeching was generally done around age five. He would instead be dressed in stays and dresses like his sisters short enough to walk in.