Things Percy and Oliver did in their dormitory and swore to never ever tell anyone

The predator laid awake, waiting for his prey. The door opened and closed, alerting the predator that his prey had arrived. Carefully, he watched in the security of darkness how his prey turned his back at him in order to get ready for bed. Slowly, the predator rose from his bedding and armed himself. Two step, maybe three, and his prey was in reach for attack. The last step alerted his prey and urged him to turn around but it was too late.

Percy hit Oliver in the face with pillow. "That's for leaving me to the Slytherins in class!"