Why she did this to herself, she would never know.
Maybe she hated herself. It was certainly a good explanation. It was a really good explanation, now that she thought about it. It would explain why she was hanging so close to the edge of human civilization, why she lingered in the shallow water, watching the reflections of fire dance in the surface above her. Watching the ones who had caused her so much misery in her existence. Watching them.
Humans. Laughing, smiling, cheering humans. Humans waving fire in torches. Humans greeting each-other, hugging and kissing. Everything that she had now been denied.
Her lips bared back to reveal sharp teeth, tail flicking the water agitatedly. The waves lapped along her back, pressing against her dorsal fin. Hands sunk into the soft sands, claw-like nails digging further and further. Humans. They were the reason she was here, stuck. Never could she venture so far into the ocean again, not while this curse afflicted her, making her cling to land like a desperate child who clings to a piece of driftwood, never wanting to get sucked far out into the sea. This curse that forced her to be one of them, for days at a time, burning underneath their harsh sun, her tongue twisting on harsh words, and her strange limbs buckling, unused to bearing a weight they were never meant to.
But for now, she was not. Her powerful muscles rippled along her tail, gills pulsating in the water, taking sweet breaths in a place that most find inhospitable. The chain mail that hung over her chest, the relic from some fallen knight, fluttered around her small torso. How good it felt to be in the ocean. But how much were her days numbered. Her black eyes darted to the moon hanging above her, fat and round. Only a sliver was gone. Tomorrow, she would be denied the ocean's watery embrace. Tomorrow, she would be forced among them.
Finally, she pushed back from the beach, puffing sand around her. She carried her trident in her left hand, a weapon four feet long with three lethal prongs. It was her comfort, the only thing that remained of her past life. Living her family legacy... Neptune. How noble and wonderful. Something that gave her a purpose.
And now? Now, she had none. Just anger. Anger that drove her onward. That made her fear and loathe these humans that ruined her life.
Her tail cut through the water, the dorsal fin slipping above the surface once, before she swam, the swift current plastering her white hair against her face.
It was night. It was time to hunt. Her lips split into a demonic grin, serrated teeth gleaming.
It was time to feed.