Best FF That Reminds Us That It Isn't the First Step That's the Hardest, It's the First Year: Habitation, by livia. Galaxy Quest, Fred Kwan/Laliari. Yes, it's het. But it's interspecies het, which helps raise the perv factor a bit. And yes, I am nominating a fan fiction story based on a movie that wonderfully skewers fandom and fannish behavior, and yes, there is some irony there. So, now that we've covered the mandatory objections, would you please go read this story right now now now? Because it is just so right, people, no matter how wrong it also is. This is FF at its best. Because, see, every marriage is marriage to alien creature. The marriage becomes real when you've become a species of two. (Help! Went too deep! Drowning in metaphor and simile! Send friendly, intelligent, anthropomorphic dolphin to save me and teach me important lessons about friendship!)
Best FF That Reveals Some Shocking Inside Information about the Magical Publishing World: Who Wrote the Book*, by Canis M.. Harry Potter, Sirius Black/Remus Lupin. HP established-relationship stories tend to feature endings - deaths, breakups, betrayals. And that's no surprise; in Rowling's world, it's hard to imagine a happy future, because everything's so hazy. Even assuming both halves of a couple do survive, it's hard to know how things will be in that still-nebulous Time After Voldemort. (Tell you what, though; I'd love to see a long-time story about Ron and Hermione with a houseful of kids. I'm convinced Ron would be another Molly and Hermione would be just like Arthur.) What I love about "Who Wrote" (yes, there was an actual nomination here - scan back up if you've forgotten) is the glimpse of Remus and Sirius without the Shadow of Doom; the SoD has come to permeate all FF about these two. I prefer to think of this as the start to an AU world, where Peter was caught, Sirius stayed free, and Harry went to live with Remus and Sirius.
Best FF That Explains the Wily Inner Workings of the Canine Mind: Likewise, by AuKestrel (no link for her, sorry). Due South, Benton Fraser/Ray Kowalski. I realize that this story may be too sweet for some people. But to me, it's a remarkable example of the long-time story; this is what it's really like when ten years have passed and it's still good. I smile whenever I read this. And, hey, she quotes my favorite REM song at the end, so the story must be good, right? (Note for the grammar-fixated, my sisters in pedantry: the comma splices must imitate the voice of Kowalski on the show. I've read other stories by this author, and she doesn't write like that most of the time, so it's a stylistic choice. Take a deep breath and go with it for a bit. I think you'll find it works.) This is just a nice look at the happier, mellower future editions of Ray and Benton, and I for one think they totally deserve this fate.
Best FF That Will Enhance Your Tolerance by Making You Wonder, the Next Time You See an Intergenerational Couple, If One of Them Is a Vampire: At a Glance, by Dira Sudis, aka dsudis. Buffy the Vampire Slayer, Spike/Xander. I've said vampire/human relationships can't work in the Buffy world, and I stand by that. But Dira Sudis has somehow found the best-case scenario here. And then some. I found myself wanting to buy into this version of Spike and Xander. I even found myself formulating strange theories to explain their relationship. ("Hmmm. Maybe they share a soul?") This is a Buffyfic that manages to be touching without angst, that is realistic and yet (I think) in canon. My early survey of this fandom shows that that is about as rare as the Questing Beast, so enjoy this one. Even if the ending is a bit ambiguous.
-Honorable Mentions (i.e., Previously-Nominated Stories That I Can't Shut up About)-
Best FF That Answers the Question "What Do You Do With an Aging Superhero?" (Take Him to Rural Areas.): I Still Believe, by Dasha (sorry, no link for her). The Sentinel, Jim/Blair. This is my favorite Sentinel story, so much so that for a while after I found this one I stopped reading in the fandom altogether. This story resolves everything so well that it made every other story seemed superfluous. I got over that, luckily for my self-image as an obsessed multi-fandom reader (for as a dog returneth to his vomit, so does this fan fiction reader return to her old fandoms), but I still re-read this one from time to time. It's wonderful.
Best FF That Answers the Question "What Do You Do With an Aging Dwarf?" (Take Him to Valinor.): Sky as Grey as Your Heart, by afrai. Lord of the Rings, Legolas/Gimli. This one is another essentially perfect long-time love story. And it converted me to a pairing I'd previously hated, canon or not. So if you've been avoiding this one - and you'd have to be not to have read it by now, 'cause it's been rec'd everywhere - now would be a good time to try something new. And if you've read it before, why not read it again? It'll give you something to remember the next time you read a story about Legolas weeping for the lost love of Aragorn and writing bad poetry ("To a Lost King" and "Sweet Man-Kisses" by Legolas Fangirl Greenleaf) and embracing his pillow at night.
* Thanks to switchknife for her merciless pimping and helpful, custom-fit recommendations. This woman is determined to drag me kicking and screaming into the deep end of HP fiction, and of course I love her for it. Though I imagine my loved ones are wanting to have a few words with her right about now.