Origin

Tanya had met Karl Lykos during their childhood, in a trip to Tierra del Fuego, where she got lost and was saved by Karl. They fell in love but her father never allowed them to get married. Karl Lykos them become Sauron, in order to achieve richness and then have the approval of Tanya's father, Dr. Anderssen.

Mayor Story Arcs

Sauron

When Sauron got to her apartment in order to kill her father, the X-Men stopped him, and then he realized that Tanya would never love him as a villain and murderer, and fly away back to Tierra del Fuego to die alone. Tanya realize that he is at her father’s old mountain house and go there by herself, only to watch Karl jump off a cliff in order to prevent himself killing her and drain her energies.  

To the Savage Land

A notable appearance was in the first story arc of the series  Marvel Fanfare (1982), written by  Chris Claremont. In that story, Tanya learned that Karl had survived the leap from the cliff. She joined  Angel and  Peter Parker on a journey to find Karl in the Savage Land. Unfortunately, he had reverted to his Sauron form and joined the  Savage Land Mutates. The X-Men traveled to the Savage Land and defeated Sauron and the Mutates. They brought Lykos back to the United States, and at the X-Mansion Professor X seemingly cured Lykos of his condition. Karl and Tanya decided to resume their relationship and a normal life.    

X-Force and Death

Toad soon remade the Brotherhood of Evil Mutants and targeted Sauron as a member. In order for Sauron to reemerge, he had to suck the life force from somebody. Toad supplied Tanya's life force to release Sauron, thereby killing Tanya in the process.