The girl is only a few years younger than his wife had been, but she is the absolute antithesis of her mother - blisteringly cold in all the ways the Princess radiated warmth.
He keeps trying to tell himself this was a good decision, but there is lingering doubt in the back of his mind about bringing an innocent into this game. Barbara Gordon, meet Batman. Post BB during The Dark Knight.
Summary: The capacity to watch is something of a prerequisite for membership in the Batfamily.
Bane never confesses to her, but she knows it as an absolute truth: he kills them for her.