A native of Edenia like Kitana, Rain, and Jade, Tanya is introduced in MK4 as appearing innocent, but is regularly portrayed in the series thereafter as untrustworthy, as she elects to serve on the side of evil, even if it means betraying her comrades in the process. In MK4, she enables Shinnok and Quan Chi to invade her home realm, and attempts to lure Liu Kang into a trap in MK4 (which she accomplishes in her noncanonical ending), but it fails as Shinnok is defeated by Liu Kang and the Earthrealm defenders. With her master gone and herself wanted by her home realm for treason, Tanya flees to Outworld as a fugitive, resurfacing as an enforcer for the Deadly Alliance, who are imposing their will upon the denizens of Outworld. When the Deadly Alliance is killed, Tanya then joins Onaga, who sought to fuse the six Kamidogu into one and thus acquire incredible power, for which she brings him to Edenia. Tanya was added to Mortal Kombat X as a downloadable character, and has a small role in the game's story mode, where she and Rain aid Mileena in her attempt to reclaim the Outworld throne from usurper Kotal Kahn upon Mileena's promise to free Edenia from Outworld's merger, a deal that goes for naught when Mileena is killed by D'Vorah. Tanya's ending has her and Rain fleeing Kotal Kahn's forces in Outworld; when they are captured, she turns Rain over to Kahn in exchange for clemency, and Rain is burned at the stake.
Source: Wikipedia, "[en.wikipedia.org/wiki/List_of_Mortal_Kombat_characters List of Mortal Kombat characters]", available under the CC-BY-SA License.