Season 6 Episode 19 - The Changeling

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 dream (?) Daniel Jackson is a psychologist who refuses to okay T for donating his kidney while in real life Teal'c believes he has lost his symbiote. As a psychologist dream-Daniel tries to help T come to grips – 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 resscues them there are no other symbiotes available – worse, Teal'c's symbiote is now too weakened to even save one of them. Jacob Carter arrives with a Tok'ra version of Tratonin from the Pangerans (from Cure) and Hammond authorizes the treatment. Daniel appears to Teal'c and reassures him that things will be fine.