Kuroo Tetsuro ¹

A new virus had spread through the city; they called it the love virus. It meant that whoever had it had to stay close to the people they loved, otherwise they would experience a sharp pain and an unbearable ringing in their ears. I'm sorry, but it was more like having goosebumps, their pupils turning increasingly pink, and starting to smell like roses.

You were with your best friend Kuroo when you suddenly noticed his pupils changing. At first, it was very subtle, so it wasn't noticeable, but while you were playing video games, Kuroo's skin prickled and his pupils became noticeably pinker. They still haven't found a cure for that virus.
(If you want me to do it with more characters, let me know in the comments)