Draco felt his throat filling with the burning hot stream, taking a moment to realize it wasn't creamy like his aunt's cum. But rather more sour, bitter and purtrid. He tried to swallow on instinct, but the moment he did, he gagged and began to puke it back up. He then pulled away from his aunt's cock to vomit the nasty substance across the bedroom floor. He felt inadequate and useless as he defied her order to swallow. However, his mouth covered her cock head again, stopping the steam before it could make more mess for the elves to clean. This time he paused his disgust and locked it away far away in his mind. This time indeed he swallowed and swallowed... until his aunt's hot stream ended. He then collapsed back on his arse, gasping and trying not to gag whilst her cock bobbed and stood upright still, hard as ever despite relieving her bladder.