Ticci Toby x Mermaid!Reader

Y/N had been friends with Toby Rogers when they lived in the same town,but when her parents decided to move they had to say goodbye.Toby was fifteen and a half when she left,before the accident that changed his life,Y/N is precisely four years younger than him, they're birthday's are on the same day.But what no one except her mom knows is that Y/N is half mermaid,after he real dad left her mom re-married.She's heard of Toby's disappearance,but would she be the first close to human person that saw him without dying.