Title: Last Chance
Characters: Sam, Jack, Daniel, Teal'c, Cam, Martouf/Lantash
Pairings: Minor Sam/Martouf/Lantash, past Sam/Jack
Category: Action/adventure, hurt/comfort, angst, AU
Warnings: temporary character deaths, violence
Summary: A new alien race has almost conquered everyone in the Milky Way. Sam has one last chance to fix it.
Prompt: 115. SG-1, Samantha Carter, any, starts post-series, maybe around 2030 or so. A really bad new enemy has appeared and the Galaxy has fallen. They have slowly infiltrated everyone (sort of a parasite or noncorporeal lifeform that can take over people). Those with symbiotes can sense them, like they can the retou, but after the Jaffa killed off the remaining Tok'ra and Goa'uld, no one is left to sense them and they were not discovered in time. The aliens spread some poison gas or radiation or something which Sam is slightly more resistant to, due to changes from Jolinar. She is chosen among the last survivors to go to a new-found alien device, send her consciousness back in time to her younger self, before the aliens took over everyone and everything. If she survives long enough to get to the device.
AO3:
http://archiveofourown.org/works/7649761/chapters/17416894Symbiotica:
http://www.sg-symbiotica.com/fic/viewstory.php?sid=637