Cassandra entered the cave in a tank top, sweat pants, and sneakers, with a towel slung over her shoulder.
She too had a routine, and this one involved time spent in the gym practicing her techniques -- especially the techniques she'd picked up on the fly from people in combat -- whether fighting them or alongside them. While her physical memory was extraordinary, it was still only short-term. Once she'd mimicked someone's technique, if she didn't spend time committing it to muscle memory soon afterward, it would eventually be overwritten with something else, forgotten as if it had never been learned.
Plus, she knew she would catch Damian down here practicing Batman things. As much as he drove her crazy with his attitude, she still wanted to bond with her new little brother. And through training with him, she hoped she'd be able to steer him in the right direction.
Hearing the alarmed chattering of the resident bats, she looked over to the target practice area. He was practicing with Batarangs, which she found somewhat amusing. She'd figured it out within a day or two long before she'd become Batgirl, but that was partly because she'd seen Batman use them against a group of gang members, and partly because she'd snagged a few batarangs from the crime scene and practiced with them for hours afterward. Damian didn't have the advantage she had, but he was already more proficient than most people would have been in the same amount of time.
As the six bats scattered, Cassandra spotted another batarang flying in their midst. That's when she realized: the bats weren't just startled because he was throwing the batarangs too close to them -- he was throwing the batarangs at them.
She heard a dull thunk. She sprinted toward them.
The small bat hit the ground just before Cassandra could reach it, and she skidded to a stop near it. She crouched and gently picked it up. It was in pain. And then ... nothing.
She held the bat in her trembling hands. And then she turned to Damian and glared.