I've been working on this story for the past month. I really like it. It is a time-traveling alien AU. No kidding.
There are specific warnings on the Ao3 page but the basics are: it's multiple pairing, it has time skips, and the main character is a slightly unreliable narrating alien.
Still interested?
Fandom: Criminal Minds
Characters: Reid, Hotch, Prentiss, Gideon, Garcia, and original characters
Rating: 14A or Mature
Warnings: AU, violence, sexuality, suicide, mentions of war/terrorism/September 11th 2001
Length: ~40k
Summary: In 1959 a naked man suddenly appears in the New Mexico desert. He has no idea what kind of adventure he’s about to embark upon. Thankfully, he’s a scientist and believes in documenting everything, otherwise the one he loves the most wouldn’t believe any of it ever happened.
Read it
on Ao3.