Having lost her parents at the age of three, Ananke grew up in a corporate, and therefore military, funded orphanage. For fifteen years, she was given the minimum required amount of food, clothing, shelter, and education to become what she was being reared to be- as soldier. The way her 'home' worked was simple: children went in, military academy students went out. If you spoke out of turn, you were punished harshly. If you failed to meet the matron's standards, you were shipped off, never to return. Ananke never found out where those children went, and only knew that she never wanted to be one of them. With her only two options being to excel or to be discarded, she made sure not to betray expectations.
The academy was much the same- you studied, you practiced your drills, and you did what you were told. By now, obeying things without question had become much easier to Ananke. She didn't do much in the way of making friends, or even acquaintances for that matter, but that didn't matter when there were teammates to lead and superiors to follow.
She was well suited to it, as much as anyone her age could be. She didn't shy away from the guns and hand-to-hand combat, and while she wasn't naturally gifted with any sort of academic intelligence, even she could figure any problem out with enough time and experimentation. When she was first shown how to kill an Infected, she neither flinched nor hesitated. After all, the stories of all the children whisked away from the orphanage, of what happened to people who couldn't succeed, was a scarier, more unknown fate by far.
The Infected were physical things. They could be sliced, burned, and killed. The possibility of abandonment and discard? That was unknowable.
When she graduated, and was recommended for the nest elimination branch, Ananke accepted her fate without batting an eye.