Thelma was a siren and member of the Mistress's pack in San Francisco.
Biography
Ninny with human appearance
Thelma, alongside Ninny, used a hypnotizing song to lure and devour males customers into bars and clubs. They found Spike, with Xander Harris, who she attracted under the appearance of a young woman with the same interests as him, praising his poetic words and comparing them with poets Shelley, Keats, and Raegan Butcher.
Thelma and Ninny guided Spike and Xander to an abandoned theater. There, they were to entertain the sirens with semi-nude pillow fight, to soon have sex with the Mistress then be killed. However, the two men, with the help of the spirit Anya, succeed in going out of the bewitchment, and killed the two sirens, while their leader ran away.[1]