Unfortunately, there's not a lot of true epistolary FF out there. Doesn't matter. I'm such a document slut that I'll go with any story that promises to mention letters or diaries. Sad, but true. Well, providing said story is good. And these are.
Best FF Likely to Lead to a Master's Thesis on the Importance of Sig Files in Modern Communication, and the Significance of the Suppression Thereof: Eros Epistolary, by Brighid, aka mz_bstone. The Sentinel, Jim/Blair. The first challenge of an epistolary story is to come up with a good reason why the characters are writing to each other, rather than, say, chatting. This is especially difficult, I'm sure you can appreciate, if the two characters live together and in fact spend essentially every moment of their lives together, which, of course, is exactly what Jim and Blair do. Brighid manages to get the guys writing to each other just fine, though. And note her fabulous use of the many options available to the modern epistolary writer, from sticky notes to email to recycled paper. Epistolary stories aren't boring! Epistolary stories are grand! Epistolary stories in the morning! And epistolary stories in the hand! Um. Stopping now.
Best FF That Shows How Addictive Letters Can Be in Bad Circumstances, So Won't You Write to Some Depressed Individual Today?: Letters Home, by penknife. The Secret Garden, Dickon/Colin/Mary. This story is not told entirely in letters. But it's about letters, and it's got extracts from letters, and it's a fantastic story, so I'm not seeing a downside here. Except the sadness. See, the problem with The Secret Garden is that it has to stand alone. Given the times and the culture in which the story takes place, there can't be a happy ending for the three of them as adults. I've always known that, sadly, the likeliest outcome was Mary and Colin married, and Dickon working as their gardener.
Except, of course, that they are on a collision course with World War I. Colin and Dickon are destined for hell in the Somme, and the odds aren't good that they'll both survive - especially not if they end up calvary, as penknife hypothesizes here. This story is something I could never even imagine - a reasonable extrapolation of The Secret Garden, one that lets the trio grow up and places them squarely in the real world. This shouldn't work. Except that it does, it really does.
Best FF That Shows How Addictive Letters Can Be Even in Relatively Good Circumstances, So Won't You Write to an Irritatingly Happy Person Today?: Written by Hand, by setissma. Harry Potter, Remus Lupin/Sirius Black, Remus Lupin/Severus Snape, James Potter/Lily Evans. Perhaps it would be better if I just wrote "assorted non-explicit and implied pairings." In any case, what we have here is a story in which Remus suffers from a handwriting addiction, and Sirius helps him figure out a way to get his fix even in Romania. It's sweet without being cloying. Remus gets down with the magic theory, we get the niftiest form of eavesdropping ever, and love prevails. At least briefly, which is exactly how long love gets to prevail in J. K. Rowling's world.
Best FF Told Entirely in a Letter That Leaves Me Barely Resisting the Temptation to Write a Letter Back1: To Casey, on His Thirty-Fifth Birthday, by Mosca, and does anyone know if she has a LJ? Sports Night, Dan/Casey (ish). Let's just get this out of the way now. I succumbed, OK? I completely and totally succumbed to the lure of Sports Night fan fiction, and if you haven't, all I can say is: run. Or the cultists will get you, too, and soon you'll be reading fabulous fan fiction about two guys who are smart, neurotic, funny, and so clearly in love that I'm surprised it was never mentioned in a daily run down meeting2. I really have to apologize for making my first official nomination in this fandom (the other one didn't count, because I wasn't in the fandom then) so wistful and unsmutty and unresolved. Trust me, there's also joy aplenty in the SN fold. (And if you won't trust me, trust the minions of Bhagwan Sports Night. They are even now waiting on your doorstep to tell you about the pure and slashy love to be found when you embrace Sports Night, for Sports Night is love and love is Sports Night.)
Best FF That Proves That Fraser and Kowalski Can Make Even a Community College Creative Writing Class Sexy: The Course, by Bone, aka thisisbone, and Aristide (anyone have a link for her?). Due South, Ray Kowalski/Benton Fraser. I love document-related fiction way too much to limit myself to just four stories; it was actually a battle of will for me to limit myself to one story per fandom. So this is today's bonus story. It's one that many people will have read; this is what we call a classic of the genre, by which we mean that it is chock-full of smut. And humor. And then a lot more smut. And this cavalcade of smut is induced, my friends, by Ray's journal entries. Diaries and smut and undercover work and smut and sullen community college students and smut and Fraser in relaxed clothing and smut. And then some smut. So, really, you cannot go wrong with this one. And if you don't know from due South? Well, you'll be able to read this anyway; I barely knew the fandom when I found this story, but it turns out that high-quality smut is truly accessible fiction. (Just think of the improvement in our nation's literacy statistics if summer reading lists included this sort of story!)
1Said sequel would, naturally, be called "To Danny, Who Will Be Lucky If He Lives to See His Next Birthday If He Keeps Leaving Tragic Love Letters on Office Computers." And it would begin "Dear Danny - I see that therapy has really improved your communication skills, not to mention your passive-aggressive behavior and your self-image. And if you think I won't read every damn file on my computer rather than write a script, then have I been sharing an office with Pod Danny for the last two years?"
2Actually, I suspect this was covered in a rundown meeting. I make no promises about exact wording, but this is what I heard:
Dana: ...and does anyone know anything about what's happening in Los Angeles? Anyone?
Jeremy: You mean the celebration of the re-opening of the antiquities collection at the Getty?
Dana: I was thinking of something sports-related, Jeremy. Because this is a show about sports.
Dana: So, in conclusion: no one knows anything, we have no script, and Danny refuses to come out from under the table, which will impair his ability to report sports news with a smile. It's going to be a great show. Guys, at least try to keep the mushiness down a bit tonight, OK? You were ready for Lifetime last night.
[Dana stalks out.]
Danny, from under the table: Lifetime?
Natalie, rolling her eyes: Please. You two are so in love it's obvious to viewers on Mars.
Jeremy, quietly, making a pathetic attempt to distract the conversation: Actually, I don't think we're big in that demographic, but -
Casey: We are not in love. We're friends. And may I say, I don't know what is wrong with this world if two men cannot be good friends without their colleagues concluding -
Natalie: - and 73% of the viewers, according to last month's poll -
Casey: - they're in love. What?
Natalie, offering Casey a sheet of paper: Poll.
Casey, reading: "I would describe Dan Rydell and Casey McCall's on-air relationship as distant (2%), warm (8%), friendly (17%), loving (22%), the clearest example of a successful and loving long-term relationship currently on television (51%)." Who wrote this poll?
Natalie: I'm surprised it was only a bare majority on that last one, really.
Jeremy: It was a direct quote from People, Casey.
Jeremy: From the article they did about the show's increasing popularity.
Natalie: The one Dana wouldn't let you read.
Casey: A quote from People? We are not in a long-term relationship! What is wrong with the world when -
Natalie: You did that speech already, Casey.
Casey: What, you'd prefer the speech about how half the Western world thinks we're fucking?
Jeremy, standing: So, I've got to go check the, um, thing with, um -
Natalie, grabbing his tie: Leave and die.
Casey: Half the viewership thinks we're FUCKING?
Natalie: Marketing thinks it's a great new angle. Speaking of which, they wanted me to show you these new print ads.
Casey, looking at print ads: Oh, for - where are they running this, Playgirl?
Casey, looking at another sheet: Oh my god.
Casey, muttering under his breath: "Remarkably flexible?"
Casey, looking at a third sheet: We're not "tender and caring and sweetly sexy!"
Natalie: Well, actually...
Casey: So if we're in love and we're sweetly sexy and Danny's already under the table, does that mean I can get a - Danny, OW!
Natalie, rising suddenly, still holding Jeremy by his tie: Now we leave.
[They flee. There is a moment of silence.]
[Casey stands up, hesitating, looking at the conference room door, then back at the table.]
[Casey crawls under the table.]