This thief is part of the Lowacks gang, and served as lookout as Iolaus ran a con on The Greedy Jeweler. In the novelization, the character also serves as a distraction to cover Iolaus's escape:
Iolaus ran, pushing his way through the puzzled crowd. Two other boys in the area took off running at the same time. They shoved into people and booths, creating even more confusion.