I read voraciously, and part of my reading does involve fanfiction (specifically, Harry Potter, Dr. Who, etc). Unlike she must not be named (E.L. James), there are actually aspiring authors out there who write some really good AUs of some of our favorite books (Unlike E.L. James) and I feel almost obligated to share them.
My first recommendation is: Harry Crow by Robst
What’s it about? What if, instead of grudgingly accepting the boy on the doorstep, the Dursleys tried to return him to ‘his own kind’? Harry Potter ends up as Harry Crow, raised by Goblins, and sent to Hogwarts with a specific plan of action in mind. A cunning Harry can make a lot of things happen.
This is a well-written piece of work, and I often find myself re-reading it. It is not, however, a short story, so be prepared for that. Harry Crow comes in at 106 chapters/ 737,006 words. It. is. massive.
Its also, unlike so many decent fanfics out there, complete!
If you like fanfics at all (and admit it, you probably do), I highly recommend you go check this one out.