What I must ask you to by verarose19. Its severitus (not biological), and Sirius/Snape. Not my typical style, but I enjoyed it There’s also when the roses bloom again by theblacksresurgence on ffn. Time travel WWII Harry/mcgonagall. Also not my typical style, but enjoyable. The ending was a bit disappointing, but it didn’t take away from the rest
If you want WIPs, check out sarcasm & Slytherin by anonymousmagpie and new blood by Artemisgirl. Two of my favorite series. The Arithmancer by white_squirrel had great world building but I disliked how it ended (though I completely understand why). And then a really off the wall fic that was nonetheless very enjoyable is strangers at drakeshaugh by Northumbrian