Burt is finally told that tests revealed Kurt is HIV+. He gets upset, because he knows Kurt isn't using, and assumes that means he had unprotected sex.
Kurt eventually breaks down and tells him that a guy raped him on his way home one day. Kurt tries to keep it all secret from glee club, even rejecting Puck when Puck tries to date him. However, one day at glee practice, he slips and hits his head on the piano. As the others try to help him, he just yells not to touch his blood.