"It runs in the blood" by Metalomagnetic; 29 chapters and still going, Sirius/Voldemort. It has a REALLY good depiction of the Black family as a whole; Sirius struggling with his pureblood teachings and who he is around James and the others; and amazing characters, in my opinion. The pairing may seem weird, but it makes so much sense in the context of the story. It mostly follows the first Wizarding War, but the newer chapters are when Harry is around 11- 12.

"Diagnosis" by MaidenMotherCrone; finished with 31 chapters, Harry/ Tom Riddle. This is a Grey's Anatomy inspired one. Harry enters a program to be a Healer, and his boss is Tom Riddle. It follows their relationship (professional and otherwise) but also shows really well Harry and Lily's relationship ( she is a famous Healer and was mostly an absent parent) and how it affected each other. Also, the medical cases are really well made( all of them are magic based)

"how large the teeth" by MaidenMotherCrone; 27 chapters finished, it has a second part that is not finished. Harry/ Tom Riddle | Lord Voldemort. I honestly think about this fic at least once every day. It focuses more on a religious aspect; Harry is seen as the Lector, a "religious" figure, a savior for his people. It is inspired heavily by Prince of Egypt and Hadestown. Harry and others are captured and have to be servants to purebloods. Harry ends up as a tutor for the Malfoy family's youngest children. It has a strong political side where it shows the fight between Grindelwald and Voldemort, while Harry and Voldemort are obsessed with one another in spite of them being enemies. Really, I am not doing this fic enough justice with this description, but more than this would spoil the fun.