Rose-Red Loverboy

Riddle x reader
Important info:
{y/n} is used with they/them pronouns, but is mentioned to be afab. Transmasc and enby friendly. They also have a fantasy illness of some kind that can't be cured, which is why they're at NRC to study possible cures. Riddle and {y/n} hate each other at the beginning. {y/n} isn't yuu, but yuuka (the book 2 protagonist in the manga) is a character. I tried to leave as much as possible vague about the reader while making them more than a piece of cardboard.