Sloane as a Balancer would require a Watcher who would be able to handle other things besides the actual battles and most dangerous parts.
Sofia was a Watcher who would not be required to step onto the front lines where the danger was.
All that she was required to do was handle other matters for Sloane so that he would be able to find his way around the city and get support in places where he had no experience.
She was technically assigned as his assistant which caused their positions of power to be reversed in an instant and made it difficult for her to be able to treat Sloane with disdain.
Upon learning such a thing, the face of Sofia became slightly frozen due to her shock.
She was about to argue back and try to plead for another Balancer to work with but she then thought back to the words of her father.
Her father had already warned her that she would have to learn how to behave in the future if she wanted to make him proud.