okay look i can't take this anymore i'm doing a proper fic rec (...kinda)
so: the Dangerverse, by Anne Walsh/whydoyouneedtoknow
Living with Danger, Living without Danger, Dealing with Danger, Facing Danger, and Surpassing Danger (WIP -- 57 chapters/406,610 words)
Current length (as of this rec): 1,786,062 words and counting
it's the AU we've always wanted, more or less -- Remus Lupin finds tiny!Harry is being mistreated by the Dursleys and rescues him. Sirius is rescued shortly thereafter, and so Harry gets to grow up with a loving, supportive family, that tells him the truth about himself and his parents, and teaches him how to protect himself without taking away his childhood more than outside forces allow.
you will actually like Harry Potter as a person/character
Remus and Sirius act like adults, more or less
(i mean, they're still Remus and Sirius in their early twenties, but they've also grown up a lot very quickly and it's great)
canon characters with little-to-no screen time/characterization get plenty of it here and they are awesome
Snape goes through a lot of stuff and it's really satisfying
eventually he actually manages to redeem himself
basically he and remus and sirius and also dumbledore are all the way they should have been in canon but weren't
so much amazing worldbuilding
you will fall in love with characters you never expected to
Neville and Ginny and Luna all actually get screen time and are utterly awesome
OCs who you will wish were in the ridge
so many AUs and ficlets of the AU you will never run out of stuff to read
it's all available in epub and mobi versions too (and more)
so much character development
you will cry over everything
you thought JKR's foreshadowing was amazing? just wait until you read this
no seriously we just found out that something that happened over nine years ago real-time was more than a blink-and-you'll miss it joke, it was a major plot point
look please just read the thing okay
it's Remus/OFC and Sirius/OFC
the writing isn't particularly good at first
no seriously, it's really long
it's only available on ff.net and one other site (not ao3)
sometimes contradicts canon (usually due to being written first)
the titular OC has been accused of initially being a mary sue
and the main flaw, which i admit is a big one -- it's heteronormative as all get out
so in conclusion, this is one of my favorite fics of all time and i really really wish y'all would read it (it's finally hitting the climax! if y'all start now it could well be finished by the time you catch up!)