Leah was a girl with the power of Genital Erosion.
Her backstory is unknown, but she is likely to have had several one-night stands that ended up too early for her, and made her feel she was merely a sex toy to all men she slept with. The storm gave her the ability to get revenge at them.
She first appears at a party where Rudy dredges her (he also tried with two other girls but Leah is the only one to give in) and takes her to a bedroom. Before they have sex, she asks him if he isn't a guy interested only in one-night stands, which he swears. After sex, however, he intends to leave without changing numbers, or even names. Leah touches his groin, giving him a sort of STD.
After searching all day, Rudy, finally finds Leah, but she's still too mad at him to cure him. Rudy then interrupts the party and publicaly apologizes to her, and to all girls he slept with only for sex. She forgives him and takes off the curse. When he starts to have her come take a drink with him, she kindly turns him down.