The BEST Jim/Seb fic I’ve ever read: Relentless Unheroic Necessary by gyzym on LJ. It’s fantastic, and dark, and completely, utterly fucked up. And really, really R. But the smut takes a backseat to the incredibly written depravity of two psychopathic soulmates. (Summary: A swimming pool, a desert, two, the ends of sentences, guns, a future in the cards and a tiger in the brush and no one ever tells you: antiheroes have more fun.)
Angst
Empty and Return by totalgeek42 on FF.net. Two quick one-shots, post-Reichenbach, one from John’s point of view (Empty) and one from Sherlock’s (Return). Very well done. They’re fast, just read them.
The Sofie Series by Morgan_Stuart on AO3. Although super adorable for most of the beginning, the 5 stories in this series get darker as they progress. Sherlock and John befriend Lestrade’s daughter, Sofie, as she grows up.
Fluff
You Can Imagine The Christmas Dinners by ardenteurophile on FF.net. Completely adorable, with a little bit of angst thrown in for good measure. (Summary: Sherlock drags John along to Christmas dinner with Mycroft and Mummy And “Anthea”, too . Over the course of the evening, John realises that everyone in the room - apart from him - seems to think that he and Sherlock are a couple. Shenanigans ensue.
Crossovers
The Magic of Deduction by TheShoelessOne on FF.net. Crossover with Harry Potter. I’m not one for crossovers usually, but this one’s more AU because there’s little mention of actual Harry Potter characters other than in passing. Really well done, adorable. (Summary: John Watson spends seven years at Hogwarts School of Witchcraft and Wizardry, where he meets the boy who will become the greatest man he’ll ever know. Eventual John/Sherlock.)