Ta'seem was a Tok'ra surgeon asked to replace the Ba'al symbiote blended with Adria with a Tok'ra symbiote named Zanuf. (10.19 "Dominion")
Ba'al managed to get one of his symbiotes into Adria, the Orici and leader of the Ori army in the Milky Way Galaxy. With Adria as his host, he would have command of the army and dominance in the galaxy. SG-1 captured Adria while she was in Ba'al's custody, not knowing she was a host until she regained consciousness onboard the Odyssey.
Not trusting anything that Adria/Ba'al said or offered, Carter proposed substituting a Tok'ra symbiote so that Adria could be used to command her army to leave the galaxy and to determine the outcome of the team's use of Merlin's anti-Ori weapon, the Sangreal (10.14 "The Shroud"). She contacted the Tok'ra and they sent Ta'seem and his surgical team, along with Zanuf, the Tok'ra symbiote who was willing to blend with Adria for this special, dangerous mission.
Ta'seem recognized Vala as Qetesh, but Vala told him that things had changed. Apparently, he wasn't the one who had removed Qetesh from her. He was aware, however, that Vala was the mother of the Orici.
Carter remained in the operating room while Ta'seem performed the procedure. He explained what he was doing as he performed each step. Stubborn to the end, the Ba'al symbiote released a toxin into Adria's nervous system, which prevented Ta'seem from implanting Zanuf. Ta'seem finished removing Ba'al, and advised Vala that it would be humane for them to complete Adria's death because she'd suffer greatly otherwise. As he was about to inject additional toxin into Adria's IV line, Adria regained control of her body and used her telekinetic powers to throw Ta'seem against the wall. Despite everyone's best efforts, Adria managed to keep them from stopping her as she ascended.
--DeeKayP 10:35, 7 July 2007 (PDT)