In Leo's Tekken Tag Tournament 2 ending, it is revealed that Emma once worked for the Mishima Zaibatsu. In Steve Fox's ending in said game, Emma is revealed to have been a scientist put in charge of observing Steve (or, as the other scientists insisted on calling him, Subject NT01). She was the only one to relate to him as a human boy rather than an experimental subject, but was admonished by her superiors for unprofessional behavior and relocated. Nonetheless, she was still able to help Steve by declaring NT01 dead at the age of 6 while, in reality, he had been transferred to an orphanage.
In Steve Fox's ending in Tekken 7, Emma was mentioned by Steve, who referred to her as Dr. Kliesen, when he finally interrogated his biological mother Nina Williams. Nina explains to him that the Mishima Zaibatsu were trying to create supersoldiers through genetic engineering, and that he was created using her genes. While the experiments were unsuccessful, Steve was one of the survivors. Sometime during these experiments, Emma was relocated to another position and was later killed by Kazuya Mishima; the exact nature of her murder was undisclosed.