You didn't seem to read it properly?
She fears him after seeing what he was capable of doing, he betrayed, backstabbed and abandoned everyone all for his survival.
Granted HE IS a child and that's all he's learned to survive, including cold-blooded killing, but she has no reason to rehabilitate him. Keeping him at a distance, even if it means sending him to prison is what she saw necessary for HER survival, because she too only knows that far.
SHE CHAINED HIM TO THE FLOOR OF A CAGE??? does she think her knights don’t kill?? she manipulated the shit outta most of the adults around her and almost killed someone but she’s “in the right?” he, a starving CHILD, killed someone to earn favor.. and tried to KEEP GAINING FAVOR by helping her only to be sent to prison. that’s fucked.

SHE SENT A CHILD TO PRISON?! SHE PUT- THE ONLY POC ML IN CHAINS AND SENT HIM TO PRISON?! IDC IF HES AN ARSONIST HES A CHILD!! Σ(っ°Д °;)っ