Knock him out physically...

You walk up to him and grab him by the hair, lifting him to his feet. "Aow, aow!"

You then let him go and punsch him HARD in the upper gut. His breath gets knocked out and he´s gasping for breath. You then slam your hand at the tip of his chin, twisting his head a short bit at high speed which jumbles his brain a bit.

William falls to the floor completely knocked out. You may have given him some brain damage, not that you care. You stuff him back in the closet again and tie him to the walls with magic bonds.

After dealing with this minor disturbance you walk back to the bed, slide in under the covers and snuggle up next to his mother. The scent of her sweat and a faint hitn of perfume helps you relax and before you know it, you´re sleeping again...