The Lazarus Siren
In the League of Assassins, it wasn't common knowledge that Ra's al Ghul enjoyed listening to music and talking to the singer after her performance.
However, he refused to write down or record her songs. Damian only met that singer once: a redheaded "siren" who emerged from the Lazarus Pit and sang a song. It took away his Pit Rage. He then learned that his grandfather and this mermaid were old close friends and that she visited him once a week to sing for him. He would swim with her, too. He wanted to swim with a mermaid, too! He just learned the pit had fishes in it!
Jazz enjoyed talking with her friend, Ra's, and she didn't regret meeting him all those years ago when he joined her in the waters of the Ghost Zone. After she had fallen into the Abyss, Zone. and became a half-mer. Danny and her parents were shocked, but after Frostbite assured them that everything was okay, she enjoyed it. To swim in It and talk to the others. Maybe she should take a swim in the Ocean again in the future.
For Ra's al Ghul, Jasmine the Mermaid was one of his few close friends. He enjoyed talking with her very much. Even when she complains about her brother and then the training of his grandson. In return for stopping his training, he could spends more time with her.
Damian can start training again when he is 14 years old. He should find a way for her to see a Nice lake or River to swim. Maybe he should build that Pool that Vandal had in his own base.