Based off Fubuki Shirou and his younger brother possessing him.

Choose either older or younger brother.

(B/E/C) - Brother's eye colour

(B/N) - Brother's name
-.-
"They were just lies!"

She screeched, hands curling into fists.

She was sick and tired. Sick and tired of lying. Sick and tired of being the villain. Sick and tired of taking everyone's faults as her own.

"Do you guys not know of pretenses?"

She continued, eyes snapped shut. They stared at her, mouths widened.

She was...upset?

"I get it. I fucking get it!"

She screamed, tears prickling the corner of her eyes.

They stepped forward, to try to calm her down but clearly she didn't want or need help.

She merely inched away.

"(Y/N)?"

"It's (B/N)! (B/N) Fucking (L/N)!"

She screamed, eyes twinkling (B/E/C).

The sudden change of her eye colour merely startled them as she screamed while tugging locks of her hair.

"(Y/N), stop it!"

A certain duo colour-haired male ran up to her and gripped ahold of both of her wrists. She merely wriggled his grasp off her and slapped both his hands away.

"Shut up! I'm (B/N) (L/N)!"

She screamed once more, backing into a dead end.

Just what happened to the composed and silent yet sweet and caring (Y/N) they knew?
-.-
Brief explanation : The reader is mentally unstable after she couldn't balance out both of her personality and her younger or older brother's personality. She breaks down and Yuya and his group tries to help her.

So in short, she suffers from Borderline Personality Disorder.