The Eternal Dungeon, a historical fantasy series on gay D/s love in a Victorian prison, has proved to be the most popular series I've written. Its omnibus e-book received three honors in the Rainbow Awards 2011, including winning the Best Gay Fantasy category.
The Eternal Dungeon is ten years old this year. I'm in the midst of bringing out new stories in the series. If you've never read The Eternal Dungeon, then you can start here, with a couple of free stories that introduce the main characters in the series:
The Unanswered Question. No weapons, no allies, and no guarantees that he will survive the test.
The Breaking. The prisoner knew that the Eternal Dungeon was a place where suspected criminals were broken by torture, and he was prepared to hold out against any methods used against him - except the method he could not anticipate.