Origin
Tanya is a Edenian brought up in Outworld well known for being traitorous, her attraction to forbidden magics has drawn her into the service of the fallen elder god Shinnok, aswell as the sorceror Shang Tsung and the necromancer Quan-chi.
Deception
After the Netherrealm war, Tanya stood with Quan Chi to act as an enforcer (or ambassador) for the Deadly Alliance he maintained with Shang Tsung. However, after they were ambushed by the ressurected Dragon King Onaga and seemingly killed by Raiden’s sacrifice, Tanya was leaderless and wandered back to Edenia. Baraka and his Tarkatan minions ambushed her and offered two choices – to serve Onaga or to die. After pledging her services to Onaga, she took him to the realm of Edenia, where she thought she could find an ancient spell to fuse the six Kamidogu amulets into one, granting the owner of such item overwhelming power.
In her Deception ending, she was able to find the spell, which has allowed Onaga to fuse the amulets. But Tanya was able to betray Onaga at the last moment, killing him and snatching his item, so she could have the power for herself.
Mortal Kombat X
Tanya appears for the first time in the alternative timeline, in Kotal Kahn’s chapter from Mortal Kombat X’s Story Mode. She appears among the insurgence team leaded by Mileena. When Kotal defeats and is about to kill Kano, Tanya ambushes him. He then remembers her as the one who freed Mileena, and Tanya reminds him she did so because Mileena vowed to do something he refused to do: free the realm of Edenia. Kotal responds that Outworld stays united against its enemies, but Tanya refutes that it’ll never be united under his rule. They engage in kombat, and Kotal wins, calling Tanya a fool for trusting Mileena.
Tanya appears later in the game’s story when D’vorah’s chapter kicks in. When D’vorah and Cassie Cage go check out the base of Mileena’s rebellion, they find out Rain, who gets to engage D’vorah in kombat while Tanya ambushes Cassie. Once Cassie gets knocked-out by Tanya, her attention turns into D’vorah, who was trying to enter the tent where the amulet was hided. Tanya stops her and mocks about their species. D’vorah only says that their species do prefer solitude… something that she would recover momentarily. After defeating Tanya, D’vorah was about to slay both Rain and Tanya, who were inconscious at the moment, but Cassie stops her and reminds her of the mission at hands. Tanya’s whereabouts after that event are unknown.
In her Arcade Ladder ending, after the abrupt end of Mileena’s insurgency, her allies have scattered; among them, there was Tanya and Rain. Even though Rain has become a powerful ally and a satisfactory consort, she concluded his usefulness has worn off. In exchange for leniency, Tanya informed Kotal Kahn of Rain’s whereabouts. He was then executed, and Tanya was imprisioned, but alive. And so, Tanya’s plotting began anew.
Creation
Tanya debuted in the fourth Mortal Kombat game and is named after the creator Ed Boon’s sister Tania.