Man, the Methods of Rationality had some of the best OCs... with Draco, Quirrel, and Fred and George.... Look I've neither read the books, nor watched any move past the second one (and I only watched those two when it was in the cinemas)... so they're original to me, ok?
A fan-fiction that I find hard to recommend, not because it is dead or incomplete (although it is boath) but because it has been lost to the ether, is The Black Company In Equestria, by UnderscoreWV.https://web.archive.org/web/20150107155 ... -equestria
The Black Company in Equestria, was so good of a fanfic that it managed to exist for four whole chapters (out of 9) without introducing a single talking horse, whilst being on a website devoted to My Little Pony fiction. A cross-over fanfic of lesser-stature would have never been able to be greenlighted.
It also had a location-name worthy of Erfworld. I mean Windsoar
Castle is just topnotch.
Although it's listed as incomplete, I like to imagine the Analyst died during Chapter 8, The Storm, leaving him unable to write the ending.
UnderscoreWV also did an ASOIAF cross over with The Black Company called "Welcome to the Menagerie". It's not as long, it's just as incomplete, but atleast it is readable. (What am I doing recomending incomplete fics?) I'm just pointing this out since it's a little known fact that this one person did two Black Company cross over fics on two seperate sites.https://www.fanfiction.net/r/10598910/
Anyways, if I were to recommend a Fan Fic that is good, and complete it'd be The Black Company in Middle Earth (which even has its own TVtropes page). In those days, the Black Company was in service to the Eye of Barud-dur... https://www.fanfiction.net/s/6668903/1/ ... ddle-Earth
None of these fics require reading of the Black Company to read them (although the first one does require a Time Machine). But the MCJunker one is pure gold, just read the first paragraph:
In those days the Company was in service to the Eye of Barad-dur, the Dark Lord of Mordor. I'll never understand why these raving sorcerous overlord types give themselves names like "Bloodfang the Foul," or "Lord Slaughter," or whatever. It can't possibly earn them universal acceptance. If I was an emperor, I would call myself "Lord Galadel the Kind," or something like that. No one could object to being ruled by somone named that. Then I could rule my conquests with an iron fist and no one would revolt. Think about it- would you rebel against someone named "Galadel the Kind"? You'd feel ridiculous.