Selmak was one of the eldest of the Tok'ra and was a member of Egeria's older children. Selmak was also different in that it placed little emphasis on gender roles and would switch depending on the host. Selmak never saw itself as a leader and held a healthy suspicion for those who sought power though they acknowledged that it was a necessary trait in the organization of the Tok'ra.
After the disappearance of Egeria, the fate of the Tok'ra almost ended that day with many symbiotes being captured by the Goa'uld. However, it was Selmak and the elder symbiotes who gathered the remaining members of their kind and fled into hiding. It was Selmak and the others like it who formed the first Grand Council that codified the Tok'ra into their goals of infiltrating their enemy and destroying them from within. Since then, Selmak had offered advice on critical decisions and declined the more administrative duties of its position. As such, its actions were not forgotten and it was remembered for the role and was both loved as well as revered by the younger generation of Tok'ra symbiotes. Something that does become a problem for it as it accepts being loved by the Tok'ra, but attempts to dissuade its younger brethren from revering it through the use of humor that was enjoyed by its former host, Saroosh.
None of the Tok'ra would attempt to persuade it otherwise from entering into covert operations despite the age and failing health. It found renewed strength through Jacob Carter and felt a sort of kinship with the Human, considering he too was near the end of his life in both his health as well as his career. Selmak was grateful for the chance to continue the fight against the Goa'uld and enjoyed the company of a man whose smile and unpretentious manner endeared him to it almost immediately. Furthermore, Selmak gained something new which was family, which was something rare among the Tok'ra for most of their hosts had lost theirs. Even though Selmak mourned for Saroosh, it shared in its partner, Jacob's, pride in his first born child's accomplishments. (RPG: "Fantastic Frontiers: Stargate Season One")
Eventually, Selmak succumbed to old age. It offered to sacrifice itself to save Jacob, but despite the risks, he had to hold on as long as possible, figuring they might need its help to destroy the Replicators. It helped find the Dakara superweapon (taking control of Jacob at one point for what seemed to be the last time as it never seemed to emerge again) and after helping Jacob program it and used it against the Replicators, it went into a coma. It no longer had the strength to save Jacob and died with him soon after. (SG1: "Reckoning, Part 1", "Reckoning, Part 2", "Threads")
- In an alternate reality, both Selmak and Jacob Carter were still alive in 2006. (SG1: "Ripple Effect")