Harry narrowed his eyes at him, "Sorry Professor - can’t have you shouting and bringing the whole school down on us," he said mildly as Snape continued to rage at him. When he made to advance on them though, Harry jumped into action, conjuring thick ropes from his wand that bound themselves tightly around the potion’s professor, snapping his arms to his side abruptly. Anger gave way to pure shock that seemed to freeze the man in place, and so he did nothing to resist when, with a sharp jab of his wand, Harry forced the professor backwards and onto the chair by the fireplace, the one he usually sat in when Harry came for their twice monthly meetings. The ropes around his waist reworked themselves to bind his arms securely to the chair, so that only his hands were free to move.