From slytherin_gypsy:

Title: Right Place, Wrong Time.
Fandom: Psych.
Pairing: Shawn Spencer/Carlton Lassiter.
Categories: AU, Angst, Romance.
Length: Epic.
Warnings: None.

Author on LJ: regann
Website: n/a

Author's Summary:
“17-year-old Shawn has a fake ID burning a hole in his pocket, a college party to crash, and a mission to stop being the only virgin in his senior class. Unfortunately, there's this big-earred, good-doing grad student by the name of Carlton who catches him in the act. The unfair nature of cosmic humor being what it is, thus begins something that'll come back to haunt them both over ten years later -- when an adult Shawn Spencer decides to give psychic investigation a try.”

Review:
Shawn has never managed to forget Carlton Lassiter, the first guy he ever slept with, despite the terrible way they parted (the older man broke things off because he didn’t want to deal with the risk involved in sleeping with someone who was underage at the time). Over ten years later they finally meet again, only Lassiter doesn’t seem to recognize him at all.

Regann manages to capture the lighthearted feeling of the show (something that, surprisingly, is not that easy to find in the fandom, which seems to delight in producing dramas), while also adding depth to the characters and their relationships. An intriguing plot, great characterization and a happy ending make for a wonderful fic.

Right Place, Wrong Time (Link to all parts)