Garwin Chang is a human boy that was in Sophie's high school senior class. He was only in one scene in the entire series, an early scene in Keeper of the Lost Cities. In that book, he wears a T-shirt saying "BACK OFF— I'M GONNA FART!"
He was one of the many kids that teased Sophie, though he teased more people than just Sophie. After she answered a question from Mr. Sweeney, the teacher, he said to her, "Nice job, Superfreak." He was bitter that he had been rejected by Yale, while Sophie, who is much younger than him (around five or six years younger), had received a full scholarship. However, her parents turned it down because they didn't want Sophie to get so much attention.
“Nice job, Superfreak.”