I'm pretty sure both were posted to sherlockbbc
, but alas that comm has no content tags, so no chance in finding them. Though I have tried. AO3 wasn't helpful either, so I am relying on you wonderful people!
1) John's trapped in the Vampires' coven and Sherlock claims him for himself. Lots of Sex and Powerplay, the main thing is that John doesn't want to be turned into a mindless Thrall. And Sherlock doesn't want that either, but the other alternative is to turn John.
Series stopped at that point, would love to see if it got further (and read again).
2) This ones an "oldish" story, meaning shortly after S1 came out. Thought I read it on AO3 but haven't been able to find. It's Vampire!Sherlock and Werewolf!John and I'm not quite sure whether they find out or already know, but in their other forms they are VERY antagonistic towards each other and they go on a rampage hunt/fight/rage through London.
The next morning Lestrade comes to ask for help with the strange occurences all over the city.
Thank you so much in advance!
P.S.: Why is there no werewolf!John tag? ;-)
ETA: Both found! Thank you, everyone!