It's Merlin/Morgana, set between S2 and S3, and it's called The Flavor of Midnight. 6300 words, and very definitely NC17.
2. Voting for challenge 6 is currently going on at the A/G LAS. Four fics this time around, on the angsty side since that was one of the challenge requirements. If you have a few moments, please head over to vote.