I really enjoy @Mirage 's and @anon50803445 's Neviro concept for the Abyss Sea, so I decided to write my own little story about his transformation and introduction with some other sirens! Sorry if the dialogue/characterization is kinda shit because I’m not used to writing it. Also, part of this writing is based on the idea of sirens living in their own little cave families.
CW: Gore and Implied Cannibalism (?)
Somewhere in the Dark Sea, under a seemingly never ending storm, lies an arctic prince of the now eviscerated Winterveil. Neviro, staring up at the clouds from an island’s ground, had forgotten how much time had passed, how long it had been since he saw Iris, Morden, anyone he recognized. The stinging pain of magic imbued, torrential rain seemed to halt any movements he made and numb his mind, forcing the man to surrender.
“I’m going to die,” he thought weakly.
“Born a failure to the Boreas name and now dying as one.”
The future he had hoped for Winterveil, the steps he took to make his family proud, everything had meant nothing now. An overwhelming guilt and sorrow washed over Neviro, but they would go unexpressed. His expression remained empty, his tears did not fall, and his gaze remained fixed. Nothing he did would matter to the Dark Sea, everything within its grasp would continue as it was, consume the souls who dared to venture into it, so why would anything he do matter now? Neviro shut his eyes and succumbed to the torment of this ocean’s corrupt nature, feeling its downpour shift from agonizing punctures to calm pitter patter. He had every expectation of dying there, in no part of his body did Neviro think to wake up, but the Dark Sea wanted something more. It thought the prince could be used for other purposes. It thought he could become part of its ecosystem.
He woke to a pain he had never felt the likes of before, not from the ocean’s storm, but from inside him. Neviro felt as bone tore through the skin of his back along with his apparel, his skeleton mangling itself into something new, something horrid. Flesh ripped from his feet as they made room for whatever was larger, sharper growing in place of them. The destruction of his once human self made the man wail and cry, to whom he did not know. Everything that had happened made Neviro hurl, and he’d writhe in that state for however long. After what felt like hours, he collapsed, now with the features of an avian.
Rain moistened Neviro’s skin.
Wind tangled his hair.
Someone gave him warmth.
As he slowly blinked back to consciousness, Neviro found himself curled into a fetal position, feathered wings encasing his bare body like a makeshift blanket. His thoughts were foggy and distant from the whiplash of feelings, not knowing how things shifted from agony to serenity in a matter of seconds. Under his head rests the lap of a woman, softly smiling above him as the prince turned to face her. She had placed her hand in his hair and toyed with it.
“Why hello there, little one. Did you sleep well?” she said.
The woman was older than Neviro, seemingly close to the age of his mother. Her presence was tender and soothing, her voice was melodic and calm. If he could, Neviro would answer her question, but his delirious mind prevented him from doing so. The silence between them was cut short as two other voices echoed through the cave and moved closer.
“His hair, it’s like freshly fallen snow. And those red eyes, he’ll fit in just perfectly!” one stated.
“My goodness, look at his wings, they’re just gorgeous!” another added.
“Now now, give the boy some space you two. He’s probably just as confused as you were.”
Words were exchanged between the three, some about Neviro’s appearance, others regarding the two’s excitement; however, none of them were ever processed by him. All the man could think about was his hunger, stomach growling and mouth salivating. The eventual hint of blood in the air made his interest peak, as his head turned and eyes focused on a heap of meat nestled into a corner of the cavern. Without thinking of how pitiful he may look, Neviro hastily crawled to the food source, tearing off a chunk of flesh and shoving it into his mouth. The sinking of teeth into meat had never felt so satisfying in his life, it made him crave more of whatever he was eating. Portion after portion was consumed by Neviro until it made him feel ill, being physically unable to continue. He lazily brought his knees to his chest and sat there, his naked self now curled into his wings and caked in the blood of himself and god knows what animal. A hand grasped his shoulder and caught his attention, gaze shifting to the woman who had cared for him earlier. She held out a gown made of flowy, light fabric.
“This is for you. My apologies for the rushed sewing, we weren’t expecting your arrival,” she uttered.
“Thank you,” Neviro responded, gently taking the cloth and draping it over himself.
After doing so, the prince stood, examining his new form. His thighs had grown feathered and soft, his nails tapered to sharp points, his calves were taloned and thin, his teeth became carnivorous, and, most notably, his back had sprouted two large, elegant wings. This appearance should’ve frightened Neviro, he knew it should, but, for some reason, it didn’t. It felt like him.
“I’ve turned into a siren, haven’t I? The wings, the feathers, they’re all quite characteristic,” he said.
The lady nodded and chuckled, “Precisely. I knew you’d be the knowledgeable type.”
“But, where am I, exactly? This isn’t-”
The woman cupped Neviro’s face in her hands. It reminded him of the rare moments in which his mother would do the same; although, those memories seemed so far away now.
“You’re home, that’s all that matters. We’re all going to look after you now, alright? Everything you need will be right here.”
He nodded and shut his eyes, relaxing into the siren’s hands as she spoke.
“It’s a blessing to have you here, young man. Our own little snow angel.”
TL;DR: Neviro gets some siren moms who actually love him
I DON’T KNOW IF THIS IS CRINGE OR NOT SOMEBODY KILL ME 
also I’m not fully aware of the Abyss Sea lore so forgive me if anything’s wrong