I am probably going to end up abandoning this, but it's fun while it lasts. Anyway, this letter was "written" halfway through season 5, episode 4. So... On with it!
Edit: The strikethrough lines weren't showing up, so anything underlined means Dean wrote it, then crossed it out.
August 4th, 2009 2014
Cas,
One of the douches in the sky dropped me five years in the future, and everything is fucked up. You don't have any mojo, are having orgies and doing drugs. I'm an asshole, Sam's missing and post-apocalyptic zombies are roaming the earth. I swear, this is like that time I got a concussion after a ghost hunt in Nevada, and I kept mistaking Sam for a girl. That was a really trippy week, everything was backwards or spinning. Anyway, back on topic, the Croatoan Virus. Extremely dangerous. What I got from myself (That is so weird to write) is that it is a demonic virus that was created by the devil or something? I don't really know, I was panicky after finding out Sam was missing. Back to an earlier topic, dude, future you is literally a hippy. You had a fucking bead curtain. And a harem of hot chicks. Like what the actual fuck. No. It was kind of awesome Why wasn't I participating?
Apparently future me was supplying other you with drugs? I have no idea why, but they definitely had a deal or exchange or something. They kept looking at each other too, but they weren't like, glaring. They were just kind of staring at each other. Do we do that? Sam is always bitchy about that kind of thing. Is it the profound bond?
Makes me feel kind of lonely
I wish you were
We're doing some kind of raid tomorrow, on a building where Lucifer is suspected to be. If you were here, we could really use you. But you're not, so wish me luck. If you even get this.
Sincerely,
Dean Winchester
Castiel could feel his eyes widening as he read the short letter, as he never really asked the details of Dean's time in the alternate future. He was confused as to why Dean kept crossing out sentences, instead of just writing what he wished to say. He flipped through the pages of the journal, surprised at the number of words on each page, and how they seemed to generally grow in length throughout the pages. Slightly unsettled, he closed the journal and placed it on the side table next to the bed. He laid on the bed, eyes closed. His last thought as he drifted to sleep was that he should probably read them all before talking to Dean.