In the eerie glow of jack-o'-lanterns, the siblings, dressed as the devil and a fallen angel, sneak away from the party. In the shadowy corner of the haunted house, she whispers, "Trick or treat?" as she unzips his costume, revealing his throbbing erection. He smirks, "Both," and proceeds to ravish her, their bodies entwined like serpents, their moans echoing through the spooky halls, a symphony of forbidden lust.