Calum was the "bad boy". The smoker, the drinker, the fighter. He had tattoos all up his arms and multiple piercings. He demanded the respect of everybody else, and scared even the teachers.
Luke was an outcast. The weirdo, the freak, the rich gay boy, who couldn't even buy himself some friends. He was bullied, beaten up daily by a childhood friend. Everybody knew who he was, but nobody really cared about him.
When Calum saves him from his bullies, Luke is confused, but soon discovers that underneath the bad boy image, Calum is more insecure than he is.