Could you do a scenario where Yoshitoki finds out Arima was the king all along and had betrayed them?

I love Yoshitoki! Thank you for the ask! 

Arima walks into his office, exhausted even though he just awoke. 

The Rushima Landing operation will be soon. Eto plans to escape soon. And, if everything goes correctly, Kaneki Ken will kill him. 

He’s sorry for what he’s done to Kaneki. He hopes he will forgive him, someday.

And then something hurtles towards his face, and he barely dodges it.

“You bastard!” Yoshitoki can’t help but feel pleased that his visibly aging brother is weakening. He slams the door shut and takes a step closer. “Is it – is it true?”

Yoshitoki’s eyes are wide and desperate. Arima doesn’t know how he knows, but he does,

“Why do you ask what you already know?” He delivers his sternest glare. If Yoshitoki interferes with his plans, he will have to kill his brother. And Yoshitoki knows he can.

But, truthfully, he doesn’t want to. He wishes he could like his brother.

His brother is what he might have been if not for Eto. Kind and gentle, forced into a role that he took up in his eagerness to please their unappeasable father.

“What are you planning?” Yoshitoki doubles over. “You’re the king. Arima – Kishou – don’t you care about us? About Father? About Matsuri?”

“Matsuri’s better off without his role. You and I both know it.” Arima is still pissed they made his nephew marry Iyo. Neither kid deserves or needs the other.

“I have to stop you.” Yoshitoki scowls. “I don’t want to.”

“Do you?”

Yoshitoki steps closer. “You stood next to me, all those years, lying to Father. You stood as our beacon of hope, and you let us lie for you.”

“Yes.” Arima looks at the floor. “Do you want me to apologize? I can’t give it to you.”

“I want – my family. That included you, or so I thought.” Yoshitoki shakes his head, and Arima sees what Eto might have seen in him long ago. 

He sees what could have been, if not for their father.

He should give up on his brother. But he persists. “I know you think you’re doing right. But do you think Matsuri is happy? Your boy likes men, Yoshitoki, and that’s nothing to be ashamed of.” 

Eto had once slapped him for not encouraging Yoshitoki to help the bookish Matsuri. 

Well, I’m doing it now. 

“H – he can’t,” pleads Yoshitoki. Father won’t allow it.

“You helped implement this. So did I. At least I will take it out.” Arima steps closer. “And you can help. If you go to Rushima now, if you let my plan fulfill itself, you can help make the world better for your son. I know you love him.”

Like he loves Kaneki. 

Yoshitoki hesitates. Arima could kill him otherwise. But, maybe, all his years of good parenting weren’t enough. Maybe Matsuri and all the Washuus are caged.

He’s always known. And done nothing. 

He meets Arima’s eyes, tears in his own. The two men exchange a nod, and Yoshitoki whispers, “Brother.”

Then he leaves for Rushima.