I can't remember whether the piece was on fanfiction.com or archiveofourown.org . Basically, Loki is now a professor/teacher to new recruits at SHIELD. This is post-Avengers and is not compliant with the current Cinematic Universe. So this is after Loki has lead the Chitaru invasion and everything and I'm guessing he's turning a new leaf now. There is a pretty memorable scene where he throws a student out the window because they aren't listening to his lecture. Also, another time when there was invasion on SHIELD, it might have been Hydra, and Loki throws out an invader out of his window for threatening his students.
If anyone can link me to it I would appreciate it so much!!! And I'm so excited to get really involved in this community and share some pretty awesome fics that I've read over the years!!