Harley is Clamp's older brother, and lead singer of the band Stompbox. He has a rare condition that makes him absolutely perfect, which sadly doesn't affect Clamp, who resents him greatly. One of the other side-effects is that Harley glows in the dark.
When Harley's band plays the Halloween party, he ends up sleeping with Tina, which breaks Clamp's heart...
ARSE TYPE: Perfect, obviously!