Bruce nodded, then lifted one shoulder in the slightest of shrugs. "They graduated. Moved on. Dick became Nightwing, Jason because Robin. Then Tim became Robin. Barbara became Oracle, you became Batgirl. No overlap." He avoided mentioning Jason's death or Barbara's shooting - speaking of those failures as seldom as possible, though they were always in his heart and mind.
"It didn't matter to me that there were two; if it had, I would have said so. What mattered to me was that Barbara didn't get herself killed going out in the field again. Batgirl was - and is - her freedom." Bruce looked keenly at Cassandra to see if she understood that. That as much as Batgirl meant to her, that the uniform meant as much, if not more, to Barbara.
"It wasn't my secret to tell, Cassandra; it was hers. To you, Dick, and anyone else she decides to tell. I wouldn't betray her confidence like that, not even to you - and if our places were reversed, she would do the same for me." Stroking her hair, he softened his voice a little. "If your feelings were hurt, you should have gone to her, or come to me, and talked to us. There is nothing to be gained by running away from your problems."