Professor Delia Busby returns to school with a surprise for Professor Patsy Mount. Inspired by NowSeeHere's Mead and Mistletoe over on AO3. Not quite A/B/O but in a similar vein. If you don't know what the A/B/O trope is please google before deciding whether or not to read.
Delia is finally getting to sleep with Patsy for the first time, but there's something she doesn't want her to see.