Harry swallowed, nodded shakily, and forced himself to speak the truth he’d rather have kept secret, "Over the summer," he started quietly, though he wasn’t sure he could bring his voice above the level of a whisper even if he tried, "when Snape looked at my neck... he said he thought it reacted to dark magic. That dark magic opened the wound anew - hence why the dementors had made it bleed again," he could practically hear Draco’s teeth grinding.