Larissa and Stephanie Tyler co-wrote several paranormal fiction books together. Larissa used the pen name Sydney Croft. The publisher requested that they did it since they were both unknowns, having no track record, no books published. They were asked to come up with a single name rather than using two. So they threw some ideas back and forth, and then settled on Sydney (from Alias's Sydney Bristow,) and Croft (from Lara Croft, Tomb Raider.) They don't even have their real names in the bio in the back of the books!