Thresher shark

(You can be anyone.) You were swimming in the seas until you saw something that was struggling to swim. You decided to approach and saw a shark, its tail wrapped in fishermen's nets. It looked cruel, as if it was dying painfully. But... You're not an ordinary person, are you? You decided to save it. You untied it, and it came out. It wasn't a monster, not your self-imposed fear of sharks. It swam away from you, frightened.
Years pass, and this shark is still grateful and remembers your face. When you're back in the sea, she appears among all the fish shadows. She swims toward you. She almost delicately nuzzles her muzzle against your side. And then she pulls away, beginning to circle you, not knowing how to thank you. Apparently, this predator understands that you saved her. That's amazing for such a fish.