In 2027, Megan and Yuna were friends at first, until Yuna had started to develop feelings for Adam. Megan noticed this and had Yuna transferred to another department.
That was a manageable level of frustration for Yuna, however it was only when Megan stole the research Yuna was doing on her mother to reduce or reverse dementia using a nanochip and a small internal hard drive that Yuna attacked her. She was subsequently fired by Sarif, shortly before the attack on the Headquarters. That's when Yuna and Adam went their separate ways, although Adam did inquire Sarif about Yuna's whereabouts.
Yuna was still a natural then, not having any augmentations. She later joined the military, and tried to move on from what happened, but when the Aug Incident occurred and her mother died, she swore revenge; and through hard work and determination was eventually assigned to a T96 unit.
When the citizens split during the Mechanical Apartheid, she participated in activism, giving the augs a voice by expressing the situation to people with the song "What's going on here" by Eisbrecher, that she wrote herself. She admitted to having augmented eyes but she was still human, and they are not like the Nazis.
Her military augs like the Icarus system or what she has like the EMP shield technology which is mainly concentrated in her fingers. This ensures that the social enhancer and EMP ammunition does not work on her.
In 2029, when she meets Adam again briefly in Dubai, she keeps him at a distance. The Illuminati want to get rid of her because she opens people's eyes to the truth, and the Tyrants want to persuade her to work for them, though they actually just wanted to kill Yuna to get the shield technology.