Rachel, Cass and Colby are three sisters who only appear very briefly in Light. They are described by Sam as 'three regular kids who had never been important in the FAYZ'. They appear very briefly, attempting to rescue Sam from Gaia, going at her with tyre irons and clubs. They are subsequently burnt to death by Gaia with Sam's power.
These three characters were based off of fans from Twitter who had asked Michael Grant to put them in the book.