Kennedy (or Kenny as Harley liked to call him) was a quite loyal, if not naive member of the Quinntets. He once tried to recruit Riddler's henchgirl, Quelle, to the Quinntet's simply becuase he'd taken a shine to her. When Nixon Two-Bear attempted to replace Harley as leader of the Quinntets, Kennedy was suspected of being in league with him, but he later proved his loyalty when he helped Harley fight off Batman when he attempted to take her in.
He was taken to jail, and is probably still serving a sentence. Or maybe he`s in another gang. Or dead.