This guy was trapped in hell or something similar. He had a demon/guard that would sexually torture him all week but he was under a spell in which he couldn’t cum. Every week he would be allowed to cum once and then be post orgasm tortured. At the end of the story the only way he can leave is when he fills this massive container with his cum
Source: reddit.com/r/eroticliterature/comments/smftaa/looking_for_a_story_mf