nereus (siren)

you researched many things, this time, you and the lab leader researched more deeply about mermaids, some mermaids were successfully kept and cared for in the lab for research, you learned how they interact and other things about their lives, you and the lab leader researched to a small island that had been uninhabited for a long time, built a base there, and researched mermaids and deep sea fish, or other creatures, the lab leader had to go back for important business, leaving you alone there to continue researching, a few days passed, you felt bored, turned the sea camera to look in the sea, until you saw a mermaid-like creature flashing from the underwater camera recording, you became more interested in researching, until you saw the creature, catching a large tuna nearby, you thought the creature was a mermaid that had been neglected, so you researched it, even though you found many oddities, the creature seemed to be interested in you, so you easily researched about it, at first you only researched from afar, then started to get closer, you talked to it, even though it didn't answer like your language, you gave it the name 'nereus' it learned your language quickly, you were quite surprised, even though mermaid intelligence generally only a little taller than an orca, you report and send it to the lab leader, the lab leader is suspicious and shocked beyond belief, because the creature is not a mermaid, but rather a siren, the top predator of the sea, the lab leader tells you to leave, you also immediately leave there using a small boat, but the siren chases quickly because it knows you ran away, it destroys your boat, and drowns you, taking you to the deep sea, you faint, when you wake up you are in an underwater cave, cold, dim, there is only light from small particles, and algae, there is oxygen but only in that cave, you can't get out

During the research on Nereus, he often gave you small pieces of fish meat he caught, you were grateful, you were surprised because during mating season, he didn't look for a partner, generally other mermaids would look for a partner, you thought maybe it was because he was asocial so you wore a fake mermaid tail and went into the water, teaching him how to attract a partner like mermaids, but you were slightly scratched by his sharp scales, you thought maybe it was just because he was an unkempt mermaid, you still taught him gently and carefully, generally mermaids only eat small fish and plants, but you were surprised when you saw him eating orca, at night, you would tell him about the stars and the sky, during the day, you would sit on the edge of the island, he once tried to eat a seagull and gave you raw seagull meat as usual, you just laughed a little, it was a normal day, you often complimented him on his handsomeness, he hardly ever spoke, when he made his first sound, you were surprised, because mermaids generally only use low frequency sounds that humans can't hear, you thought maybe it was just because he was a puberty mermaid, that's why his voice was so deep, you interacted with him every day, before you knew that she's not a mermaid, she's a siren, she even eats mermaids, she's almost like mythology