In on of the Simpsons Halloween specials, Bart's evil twin lives in the attic. It is chained to the wall. However one night after Bart and Lisa get suspicious Bart is lying in bed and something in the vents is looking at him (obviously the twin). However, later when Bart and Lisa and Maggie get up there they see it just escaping from the chains. How could it look at Bart through the vents if it just got loose.