Runners by Gil Hale is set in the ATF universe, but with a twist--Vin & Ezra are teens and JD is a ten year old (Gen). Needless to say, the three aren't in the ATF, but rather have been living on the streets when they are caught up in an ATF operation when Vin helps to save Nathan's life. The addition of Vin and Ezra in his life helps to bring out a side in Chris that the rest of the team had feared destroyed for good by the loss of his family. As for Vin and Ezra, they learn that some people can be trusted, something that their life experiences to date had them doubting as a possibility.
Forsaken by zorrorojo is a brilliant Old West Magnificent Seven Slash story (Vin/Chris--of course!). The seven are chasing a real nasty bunch of outlaws and Comancheros--ones that enjoy torturing their victims before killing them, even women and children. Determined that the gang not get the gold the seven were able to reacquire during their first skirmish, Chris has them split up--sending Nathan and Josiah to bury it somewhere while the rest of them continue on the outlaws' trail. Unfortunately, Chris' group are taken prisoner and before all is said and done, Chris and Vin are in really bad shape. Most of the story then centers on Chris' response to the traumatic event, as he slowly comes to terms with the fact that he can't always protect those he cares about.. and that he actually cares about people again--Vin in particular. Oooh, this story is so good, I've read it three times already! :-)
Courtesy Gibbous by Sealie is a Magnificent Seven fan fic set in the Little Britches ATF universe (Gen). I'm still shocked that I actually read kid fic of any sort, but I have to admit that I just can't resist Vin at any age (7 in this story). JD, on the other hand, really gets on my nerves at five years old. Happily, JD's part in the story is fairly small. The main action focuses on Chris, Vin and Ezra. A woman from Chris' pasts arrives on the scene when Vin (literally) bumps into her on the street. From then on, Chris begins to spend more time with the woman, Ella Gaines. Vin isn't very impressed with her, and Ezra is wary of her, yet Chris seems to be completely blind to the woman's nature. Needless to say, things soon get interesting and both Vin and Chris end up in the hospital. I especially like Ezra in this story--he's certainly taken to "unclehood," and is extremely protective of Vin.
The Em7 Series by Brigitta B is an alternate universe Magnificent Seven serial (Gen). Basically, the Em7 team is an elite unit formed to handle problems that the other agencies can't. As such, they have authority that supersedes that of other agencies. Needless to say, the other agencies are none too happy about that, so, in addition to completing almost impossible missions, the team also has to deal with those in the government who wish to shut them down. (Not to mention a 5 million dollar contract out on the life of one of their members, family problems, traitors within the government, amnesia, various injuries, etc...) There is a heavy emphasis on the strong friendship between Chris and Vin, though that isn't to say that the other characters get short shrift. Quite the contrary, in fact, as all of the characters contribute to the story and have their own side stories to complement the main arc.
Dark Moon series (found on the Blackraptor Adult site - http://www.blackraptor.net/m7fic/adult.
htm) by Cattraine is an AU Magnificent Seven slash story (Chris/Vin). In this universe, Chris is the Alpha of a pack of werewolves. Since the deaths of his first mate and their son, he really hasn't had much interest in living, but his Beta, Buck, has been by his side, keeping him surviving, at least. One full moon, however, Chris goes off in wolf form and the rest of the pack hear his mournful howl answered by another. Come morning, Chris has a new mate that Buck can't wait to meet. Of course, a feral Vin who was raised by an actual wolf and has had little contact with humans is not exactly what Buck was suspecting...
The Magnificent Quest by Nettie Roe is a Magnificent Seven tale set in the universe of Dungeons and Dragons. It's also Chris/Vin slash, but the main focus is on the plot and the action. In this universe, Vin is an elf/human hybrid, a fact that has caused him nothing but trouble, as humans are not very accepting of those who are different. When he and the rest of the Seven uncover a plot to usurp the king, however, Vin also learns that to Elves, hybrids are very special... and powerful. Battles with Orcs, archery contests, secret pasts, evil wizards, this story has it all. I keep hoping for a sequel. :-)