I liked hopeful Dark!fic. I love unusual pairings - e.g I have a mental plot bunny in my forest of abandoned plot bunnies of Yaxley with Luna (my exception to the no teenage character rule) as his prisoner. You know she'd either drive him barking mad or push him into sanity. Same time Next Year type affairs for unusual pairings that nobody would ever believe in 'real life Harry Potterverse' (e.g. Yaxley/Minerva, Minerva/Alastor)
I like real-life situations e.g. mentioning Alastor missing an leg plus a few other parts, Filius being part goblin and shorter than the average partner, age differences (because you know Minerva finds it tough to date as she's taught just about EVERYONE).