FanficRecs A rich alternate world that reimagines canon
I avoided reading this series for a while, because the summary sounded a bit... Ordinary. Perhaps I expected a canon rehash, with Harriett getting to know Lavender better or something but otherwise going through the stations of canon as usual.
It's not even close to that. The whole world is reinvented. The divergence point is forty years earlier, when Tom Riddle decided not to create a Horcrux, and instead turned to political means. That has changed the whole landscape; many people are alive and well who weren't in canon, from the Marauders (Harry was raised by both her parents), to the Longbottoms, to Rosier and Rookwood. It's now normal for most of Britain to be Pureblood, and there are laws that specifically bar non-Purebloods from many types of employment — but Riddle wants more than that.
This all combines with elements of the Song of the Lioness to give Harry a very different schooling experience. Even when parts of the plot are recognisably inspired by canon, they're so altered (and often expanded) that you still don't know what's coming. And Harry's passionate interest in potion-brewing leads to some fascinating explorations of areas of magic that canon skimmed over, plus the opportunity to examine Severus Snape closely in his natural habitat. (His back-story, in a world where Lily Potter is alive and well, is also interesting to discover.)
Harry is quite a lot more powerful and skilled than in canon, which may put some readers off. However, for me, it was well managed. Having a supportive home life and wealthy parents, it's not surprising that she would take to her schooling more diligently, and then the difficult circumstances she gets into force her to apply herself. And on the flipside, being extraordinary is actually a problem when she's concealing a secret that could send her to Azkaban for life.
When I finally took the time to read this series, I was thrilled to have come across it. It just keeps unfolding more layers as you keep reading.
FanficRecs Epic
This is the most amazing bit of fanfiction out there. It can stand on its own. The length, depth, character and world building is astronomical. Please give this a chance even if the description doesn’t seem like your cup of tea. It didn’t seem like mine at first. I actually avoided it for a long time. Now I’ve reread it three times, which, if you look at the lengths of each book, is a hefty time investment. Listen to me internet stranger, it is truly worth it.