Hi i look for a Morgan/Reid slash fan fiction (i think that I've read it on Ao3 but i can't seem to remember), all i know is that someone keep killing Reid's bed previous partners.
At some point, the murder cases got the attention of the team, and during the briefing, Reid sees a previous partner's face.
He later on, along with a female friend, begins to search for his previous partners, who is a lot, and (i think that it shocked the team of his promiscuity.)
In the end, the killer turned out to be his friend's husband/partner, who was always jealous of Reid because his husband (who i think was his TA/ or a professor in Reid's college, the killer also went to the college with them) kept ties with Reid, and with his accomplishment, he also was the one Reid lost his virginity to.
At some point, the killer kidnapped Reid, and his friend, to kill them (on his/his partner property).
Also, at some point Reid wonder how he dated/ was involved with his friend.
Both men was hurt, and while Reid was sleeping in his hospital room, his friend and Morgan, they talk about Reid, (and his feelings for Morgan i think).
Before leaving the hospital, Reid go to see his friend.
I hope that i didn't confuse you, and that it anyone knows it.
Thank you for your time.