Teal'c starts suffering from a series of dreams where he is a human fireman, "T," preparing to donate a kidney – the people in his dream are people he knows, ranging from his SG-1 teammates to Apophis to Bra'tac. In Teal'c's new life Daniel Jackson is a psychologist who refuses to okay T for donating his kidney while in his old life Teal'c believes he has lost his symbiote.
As the psychologist, Daniel tries to help T come to grips with what is going on. We find out the dream is Teal'c mind helping him get through after he was in an ambush and shared his symbiote to keep he and Bra'tac both alive.
When SG-1 rescues them there are no other symbiotes available. Worse still, Teal'c's symbiote is now too weakened to even save one of them. Jacob Carter arrives with a Tok'ra version of Tretonin from the Pangerans (from "Cure") and Hammond authorizes the treatment. Daniel appears to Teal'c and reassures him that things will be fine.