Itachi had been writing the first time that Hidan had talked to him.
It was a rare sight among the Akatsuki. Not that they couldn't write. It just gave a sense of permanence, being tied down. Most of the members did other things instead. Sasori had his puppets, Deidara sculpted his clay birds, Kakuzu collected coins and hearts, and on the list went. The only time Hidan wrote himself was when he recorded names for Jashin-sama in his book.
What Itachi was writing was not names. It was poetry. He read it quietly over the missing Leaf nin's shoulder.
You say you want me dead.
That you hate me more than I know.
Foolish little brother.
Haven't you learned yet?
Yet you wonder how I know you won't.
That you won't kill me yet, won't try.
I do not see the hatred in your face
That I see every time that I have
To look at my own reflection in the mirror.
It was against his belief to sympathize with the heathen unbelievers, and Hidan tried to be devout. Then again, it was also against his belief not to kill or convert unbelievers to Jashin, yet all of the other members of Akatsuki were still alive.
"What do you want, Hidan?" There was no hostility, no thrown kunai like most of the other members would have done, just the simple question.
"Damn, that is depressing, even for a heathen like you."
"You know why I am Akatsuki. That is depressing. That is what I am, what I believe in."
The other ninja got up and walked away from Hidan slowly, not angry, just as if he had completed what he had needed to with his writing.
It didn't stop Hidan from hearing his words.
"Save me the lecture on going to Hell, priest. I already am."
At least he was an honest heathen. Hidan had to respect that.
After all, who else would have turned their lives into their own Hell.
So well everyone else wondered what the sharingan user saw when he looked in the mirror, Hidan knew. It was the last line of the poem, written days after what Hidan had initially read.
I see Hell burning in my eyes.