I didn't see The Death of Narcissa Black as all that dark. I've read all the books, so I went into it knowing how it'd turn out in the end, which made it less of a darkfic and more of a classic tragedy - I felt more and more pity and sorrow for her as her life continued to narrow down into its inevitable conclusion.

(And yes, there's Bob the Builder slash out there. I've seen it in the form of a crossover with the Engineer character from the videogame Team Fortress 2. Some days I think a lot of fandom activity is done out of a sense of competition.)