Title: Impossible Loyalties
Rating: Explicit
Wordcount: 8466
Pairings and characters: Sherlock/John, Sherlock/OMC (implied), Greg Lestrade
Disclaimer: Not mine.
Summary: ‘You were having sex with your tutor?’, John said, trying but doubtless failing not to sound either surprised or judgemental.
Warnings: see above, implied student/teacher relationship.
At AO3:
http://archiveofourown.org/works/382407