Nothing will EVER come close to this fanfic. All the young dudes, Crimson Rivers aside, The Seven Devils is probably one of the BEST fanfics I've read in HP fandom. Oh my god I could read it again and again and again and never get bored of it. There's no OC like Varya Petrov and never will be. I fucking love her and her strong, dark personality. And talking about the other side characters will never be enough. This is just simply masterpiece. If you haven't read it, GO RUN AND READ IT
I beg all of you to go read a Tom Riddle fanfic called The Seven Devils by thesehunprint on ao3 and Wattpad. Beautiful writing, tragic storylines, and charming characters are what made it really win my heart.