Because someone was going to do this sooner or later.
Disclaimer: I don't own Naruto.
Dear Deidara-nii,
I remember how much you hated it when I called you that. Yes, dummy, I know I'm your cousin and not your sister, but we lived together since I was two, so I suppose that sort of makes us siblings.
It's getting colder again. I've heard that it's expected to start snowing pretty soon, and we've been advised to stay inside in case of ice storms. You always hated winter, you hated the cold. You always said it was because the world "got ugly", but I think it was just because you didn't like wearing long-sleeved shirts. Of course, you never let that stop you; I remember, Masaru-jisan was so mad.
I think it's been six—no, seven—years since you left us. Iwa's definitely quieter without you, Deidara. They've finally started to slack off on the hunter nin squads they send out to bring you back.
I made jonin last week; I finally outrank you, brother mine. The Tsuchikage has appointed me to his personal guard; I've got a new partner, and I HATE him. His name's Akatsuchi; he's dumpy, scratch that, he's just plain fat, and not particularly bright. But he's some rich man's kid, so I've got to be polite to him if I wanna keep my job.
Masaru-jisan has stopped talking about you. I'm not sure if that's a good thing or not; all he ever does is stare out his window and sigh. Well, I think so anyway. He won't let me back into the apartment anymore; I've got my own quarters now, and he seems to think that he doesn't have to let me visit him. He won't answer the door when I call, and you know what would happen if I tried to rig the door; don't worry, I'm pretty sure he's still alive. We'd be able to smell something if he wasn't.
The border's been pretty quiet, and—
Okay, stop. This isn't working at all; I'm writing this for a reason, so I'm gonna cut straight to the chase.
Why?
There are many questions I wanna ask you, and they all start with "Why".
Why did you bomb the academy that day (Don't worry, I'm not mad. The place was probably gonna fall apart sooner or later; the foundation was never very sturdy)?
Why did you tell me not to go to school that day, sparing me and no other?
Why did you leave?
Why did you join Akatsuki?
Why didn't you say goodbye?
I knew you better than anyone; I think I'm entitled to an answer out of you, just once.
Niisan, you were always so weird. And I don't mean that in a bad way; I just could never understand you. I think I had a crush on you (and believe me, if I ever thought that you'd get your hands on this letter, trust me, I WOULD NOT BE WRITING THIS PART DOWN!!!!), because you were always there and anyone who bothered me had to answer to you, and it wasn't pretty.
You were a Tokubetsu Jonin already at twelve, one of the best and brightest seen in generations, and you threw it all away. Why?
I mean, was it because of your art, and the mouths on your hands? I know a lot of people gave you a hard time because of it, but everyone's allowed their quirks. People would have gotten used to it in time. I always thought it was cool; do you remember when I was six and I said that I wished I had mouths on my hands like you. You got so pale and you told me that I wouldn't like it. The way you said it was so quiet and so tense; I've never even begun to understand what was going through your head when you said that.
But then, you were always one to act on a whim. Was leaving Iwagakure a whim. Was joining Akatsuki purely a whim. Either way, I wish you hadn't.
Alright, I'm sure if you weren't already embarrassed when I called you "Deidara-nii" you really are now, so I'll stop.
I know you'll probably never read this, but I feel like I've gotta tell you. The Tsuchikage's ready to pardon you if you just come back.
And I miss you. It's really hard to admit, but I really, really miss you niisan. I just want you to come home.
I've written for long enough; I've got to go back on duty soon. I suppose I'll see you…when I see you.
And Deidara?
Please come home.
Love,
Kurotsuchi