Give me a Harry Potter prompt

One of my goals for this year is to write fic that's not for Yuletide. Since I just finished re-reading the whole HP series, it seems a shame not to make some of that fic HP.

So, I'm curious: What's the HP fic you'd love to read but have never seen in the wild? Any pairing (or gen), any plot, any point in canon.

Prompt me (and be as detailed as you like).

I can't promise I'll write all the prompts I get, but I hope to be inspired (or at the very least, talk to y'all about Harry Potter LOL).