My Little Dashie by ROBcakeran53 is without a doubt the most beautiful fanfiction I have ever read. I got very teary eyed at the ending and had the urge to write an alternate, happier ending. I know it can't possibly live up to the emotional and heart wrenching ending the author first wrote, but it helps keep me sane.
Original story here: http://robcakeran53.deviantart.com/art/My-Little-Dashie-260443804