I'm glad someone mentioned this. I was planning on posting about it but you got there before me. I adore the Harry Potter novels, they are practically my bible, but I don't mind poking a bit of fun at them once in awhile. And honestly, when reading fanfic you have to expect things to be different from the original story.
I loved reading Harry Potter and the Methods of Rationality, but it was filled with a lot of interesting and difficult to understand concepts because this new Harry is now a child genius. So I had to do some research every now and then to understand what he was talking about. But if you like learning lots of new things, or you're just really smart already, and you like to read things that make you think, then you will love reading it.
You can read it on its official website here: http://hpmor.com/
I'm currently reading a Hermione/Snape fanfic, which seemed kind of wrong at first, but the way its written makes it allright. They are some crazy plotlines, but overall it's kind of nice.
It's very long, but a good read anyways (so far, I am still missing 5 chapters)
There's a bit violence and a bit of intense situations, but no sex
My fave harry potter fanfiction is a trilogy (it is AMAZING) but it does have alot of blood and gore, so I dont recommend it to anyone who doesn't like that sort of thing. The first story is called "a second chance at life", the second "changes in a time of war", and the third "a magical world" all written by the amazing "miranda flairgold".
the link is; http://www.fanfiction.net/s/2488754/1/ ,
hope you enjoy it as much as I did.
A Challenging Match by Ecaterana
I read this Marcus Flint*/OC story and loved it! It has (what I would expect to be) a very accurate portrayal of pureblood life. The plot is very involved, accurate, and believable. There are a lot of (interesting) names; intricate and sometimes confusing familial connections; and some bits of magic are talked about, but not explained. Other than that, though, it IS a good, believable story.
*I am currently kind of obsessed with Marcus Flint. lol
absolutely ADORE this, it's a really great fic about Harry bonding with his aunt after fifth year
...Does it have smut? *blushes and runs away*
Just google "Isolation by Bex-Chan", it's a Dramione fanfic (NC-17) and it's basically the best fanfic I've ever read. It's like a classic amongst Dramione shippers.
Honestly, after reading that, I feld like telling Ron to go bugger off, Hermione and Draco belong together!