Goa'uld & Tok'ra Symbiotes
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Cure: Tok'ra queen Egeria, forced to spawn symbiotes for use in the life-prolonging Pangaran drug tretonin. Cure: Egeria sabotages the genes of her off-spring to force her Pangaran enslavers to free her. Cure: the bloated Egeria somehow manages to quickly resume normal size, enter and blend with a Tok'ra host.
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Changeling: Teal'c and Bra'tac share Junior to sustain their lives.  He dies and they are forced onto tretonin. Evolution: Anubis' fearsome Kull Warrior made near invulnerable by brief-lived symbiote's healing powers. Evolution: Anubis' queen colludes in spawning slave off-spring with genetic memories/identities suppressed.