Curtis didn't use his Gender Swap power that much and has never shown Melissa to the rest of the gang. However, she has been found out by Simon, Rudy, Kelly and Alisha later on. He made Melissa public when he wanted to join the female athletics team, where he fell in love with Emma, who only liked him as Melissa. He was also sexually harrased by Shaun, who did not know it was really Curtis.
Curtis later started to use his power more and more, in order to find out new things about being a woman. He often indicated that he prefers to masturbate in his feminine form.
One time, he masturbated as Curtis, switched to Melissa and masturbated again. This action got him pregnant as Melissa, and forced him to stay stuck in his feminine form. In order to get rid of the baby, Curtis sold his power to Seth and Melissa no longer existed.