A bully at Roo and Ben’s school. Derek McGuiness is forever making transphobic and homophobic comments, and Roo gets into frequent fights with him. Roo is ultimately suspended from school for fighting with Derek, and Rosie must stitch up a cut on Roo’s head. Derek McGuiness represents the abuse and bullying LGBTQ kids often encounter at school, which, Frankel implies, contributes to the disproportionate rate of suicide for transgender adolescents.