Damian stormed the League of Assassins base as he free's hostages being held thare. He was Bat|man now, it's his job to protect the people of Gotham who got captured. He didn't know why they got captured but he had to do something regardless.

But as Damian sent the last one out on a boat off the island, he saw familiar Demon Head robes approach, expecting his grandfather, Ra's, he stands ready, only to freeze, it's not Ra's, it's not even Talia, it's someone he was told was dead, you, his older twin.

"How are you alive? Grandfather told me you died at birth, mother agreed with him!"

What Damian didn't know was you were taken away at birth by Ra's, and he told everyone else you died, and he trained in secret, not even Talia was told you were alive until later on in life.