Hearing Parker's familiar voice brought back memories of Katherine's time in Shadow. She was only fifteen when she joined the dark organization. Most of the agents there started at this age too. Though she didn't know what Shadow was at that time, the trauma she went through was enough for her to shut herself from the rest of the world.
After several months of indoor training, Parker supervised their kill test. He probably wanted to make sure that the trainees had the guts to pull the trigger. Or maybe… He wanted to see with his own eyes what kind of monsters he was creating. Perhaps only then he would be satisfied that he could trust the agents who would do his bidding.
Thank you for reading :)