He was an attempted victim of Arthur Mitchell.
Arthur approached Scott in arcade and pretended to be a police officer. He led Scott to his van in the parking garage, where he sedated and captured him. Arthur then took Scott to a bomb shelter, where he had a toy train and tracks set up. He began to call Scott by the name "Arthur" and pressured him to put on a pair of pajamas.
At first, Scott feared Arthur and was resistant to him. Later, Scott began to feel sympathy for Arthur after he told him the story of his sister, Vera Mitchell. To make Arthur happy, Scott agreed to be called "Arthur."
After Scott promised to stay "innocent," Arthur said it was time to set him free, and gave Scott (drugged) ice cream to eat. When Scott passed out, Arthur took him to a Four Walls One Heart construction site, and attempted to bury him alive in cement. At that moment, Dexter Morgan arrived, and struggled with Arthur. He was able to save Scott, but Arthur escaped.
Later, Scott was interviewed by Debra Morgan, and he recalled exactly how Arthur kidnapped and drugged him. He also remembered a vital clue -- the logo for Four Walls One Heart.