What are the motifs in Tricks by Ellen Hopkins?

Child prostitution (and its dangers) is the underlying idea of the entire novel Tricks. Each of the characters in the novel are at some point underage, and prostitute themselves out in order to make a living.

Whitney is at the tender age of fifteen when she becomes not only a prostitute, but a drug-addict as well. She goes out of her way to find clients in order to get drugs, and finds herself sold by Bryn on a daily basis. In the process, she loses herself and almost dies of a drug overdose.