Hi,
I have read Corvus Fallere by Mouse, that is really good, it is in two parts.
you can find the story here Corvus Fallere Book I
You have also in Hermione/Snape, For the Potion Master's Amusement by snape_submiss, really beautiful story, the link below on Ashwinder
http://ashwinder.sycophanthex.com/viewstory.php?sid=20498
And You can't have one without the other by RachelW, also on Ashwinder
http://ashwinder.sycophanthex.com/viewstory.php?sid=6538
Good Reading