There was a lot of great, IC fic in the beginning, but that dwindled as the fandom slowed down and writers moved on to other fandoms (which is fair enough). Natasha is really tricky to get right, I still struggle with her voice.

I have this theory that the more time passes between canon and fandom, the more people start to rely on common fanfic tropes and characters get warped further and further away from their canon incarnations. There's so much fluff right now that finding fic which acknowledges the characters' dark sides (not even dark!fic!) is a rarity.