Some ideas for pairings: I love Snape and Kingsley and Neville, and I'm quite fond of any Weasley brother. For femslash I usually like Luna, and scarred!Lavander... and any combination of "old" female teachers/Rosmerta/Skeeter. That said, I really like new/unusual pairings, so feel free to experiment!
Some random prompts (if needed, feel free to be creative): - Goyle as a bartender (at the Hog's Head? at his own pub? In deep Romania with Victor/Charlie?) - has Petunia ever had a moment of grace, or she's always been like a withered plant who has never had enough water and sun? Is she beyond reach? (best if no Vernon in sight, but up to you) - who could be worth to become Mr Ollivander new apprentice? - Molly + a new body confidence (freckles! softness! stretch marks!) - someone unusual taking care of little Teddy Lupin - some femslash in Charlie's reserve for dragons (it's always a slash paradise, let's shake things up! Maybe Millicent?)