The Cost of Living by Doc
Stargate SG-1 | Seasons 4 | Novel, complete

When Carter goes missing on a planet inhabited by prehistoric tribes, the rescue mission runs into complications.

The Enemy of My Enemy by MissAnnThropic
Stargate SG-1 | Seasons 3-5 | Novel, complete

Believed dead after a mission for the Tok'ra goes wrong, Jack is taken as a host.

Sleepers by Alli Snow
Stargate SG-1 | Season 6 | Novel, complete

Not long after being rescued from Baal, Jack begins to experience bizarre fugue states.