Chimera is a shapeshifter with three forms. One is Yin, one her twin brother Yang, and the third is "a very nasty beast that is slightly under their control" that they call the Chimera. Yin and Yang take turns having their body, one month each. Yin's hair is half black and half white, and her eyes are one green and one blue, except right before the Chimera manifests, when her eyes are violet. Yang looks similar. They live in Hawthorne, and have recently started dating Jimmy T. They were in an institution before coming to Whateley, diagnosed with multiple personality disorder. Yang is "guy shy," and it is implied that this is because of abuse at the mental institution.
They are important in "The Devil's Dance."