Season 5 Episode 2 - Threshold (3)

Despite the best efforts of SGC, Teal'c remains brainwashed into Apophis' service, and nothing can apparently snap him out of it. The team believe him cured, but Bra'tac arrives and confirms that Teal'c still holds false loyalty to his dead "god." Bra'tac removes Teal'c's symbiote and reveals that his student must undergo a rite - being brought to the verge of death as his immune system collapses will force him to face his memories of what drove him to turn against Apophis, breaking the brainwashing.

As SG-1 watches over him and points out the illogic in his brainwashing story that he was a double-agent for Apophis, Teal'c relives memories of the events leading up to his turning against Apophis. The memories include Apophis punishing him for defending his father's "cowardly" actions, his friend Va'lar, and Va'lar later failing Apophis and Teal'c faking his death and fooling Apophis, thus learning that the "god" is anything but. We also find that Teal'c was later forced to destroy Va'lar, and the village he hid in, rather then suffer revelation as a traitor.

Meanwhile, Teal'c condition worsens and Hammond overrides Fraiser's concerns, accepting Bra'tac's claim that Teal'c would rather die free then live brainwashed. Finally Teal'c is brought to the verge of death, and even Bra'tac reluctantly concedes that the symbiote must be placed back in his student. As Fraiser renders aid, the rush of memories snap Teal'c out of his brainwashed state and he is whole and free once more.