1. Fandom Category: Harry Potter
Fic Title: Vox Corporis
Rating/Warning(s): NC-17; underage sexing (but it's really awkward), movie-canon, violence.
Genre: Action/Adventure, friendship, romance, long, AU, angst.
Why This Must Be Read: This is pretty much the story that the H/Hr crowd points to if you want a primer on the ship and a story that is thoroughly excellent. It's plotty, long, lacks any kind of character bashing, and basically does a good job of taking the existing canon and taking you in a new direction.
2. Fandom Category: Harry Potter
Pairing: Harry/Hermione, prior Ron/Hermione
Fic Title: Stars In My Belly
Rating/Warning(s): NC-17; sexy-time.
Genre: Romance, introspection, slight angst.
Why This Must Be Read: Although I don't remember the exact first story I ever read in the H/Hr area, but this was one of the first few, and damn if it doesn't hold up. More than anything, the language is what makes this story. It's a bit romance novel-y, but the way everything fits together; that works.
3. Fandom Category: Harry Potter
Pairing: Harry/Hermione, Hermione/Other, Neville/Ginny, Remus/Tonks
Fic Title: Always the Bridesmaid
Genre: Mystery, romance, fluff, AU,
Why This Must Be Read: I absolutely love the voices in this story. Each of the characters is just so independent and interesting. These definitely feel like they're the characters grown up and/or a few years down the road. Even the incidental side characters are brilliant. Mostly though, I like that Hermione makes some decisions. This is very much a story of her being at a crossroads, reassessing things logically, and following her heart.
4. Fandom Category: Harry Potter
Pairing: Harry/Hermione, Ron/Luna, Remus/Tonks, others.
Fic Title: Muggle Summer, Wizard's Fall
Rating/Warning(s): PG-13; violence, long.
Genre: Action/Adventure, romance, friendship, AU.
Why This Must Be Read: I don't even really know how to describe this story. It splits from book canon at the end of book 6 and takes place in the summer following. This story is epic. Not only is it long, but it ties in threads of the Muggle government (including the aristocracy) and brings modern warfare to Voldemort and his gang. Honestly, this is less of a romance story than it is a war novel, but the Harry/Hermione romance is a core tenant. The cast of this (both established characters and OC's or real figures) is on par with the published novels. This is an absolutely fantastic read.
5. Fandom Category: Harry Potter
Pairing: Harry/Hermione, Remus/Tonks
Fic Title: Harry Potter And The Curse of the Ovis
Rating/Warning(s): R; CRACK fic. 100% Crack fic.
Genre: CRACK, sexy-time, humor, romance.
Why This Must Be Read: I... I really can't describe this. Wait, yes I can. Voldemort gets eaten by evil sheep during the resurrection scene in book 4. Things get weirder from there. I'm not completely thrilled with the last chapter, but the first two are MORE than worth it. If just for evil!Hermione.
6. Fandom Category: Harry Potter
Fic Title: Agent Double O Hex
Rating/Warning(s): PG; crack.
Genre: Action/Adventure, Humor, AU.
Why This Must Be Read: Harry gets adopted by James Bond and Hermione is a Bond villain. That pretty much covers it.
7. Fandom Category: Harry Potter
Pairing: Harry/Hermione, Ron/Luna, Remus/Tonks, Nevil/Ginny, many more.
Fic Title: Harry Potter and the Sword of Gryffindor
Rating/Warning(s): NC-17; crack, sexy-time, kink. Also, do not try and read this all in one sitting. I've been told that it gets a little.. overwhelming if you do.
Genre: Humor, smut, action/adventure, AU, friendship, romance.
Why This Must Be Read: This story is unbelievably funny. There are so many 'and then!' moments I can't even list them. Basically, this is a really, really raunchy sex-comedy that mocks and loves its source material in equal measures. It's basically "What if Dumbledore was RIGHT and Harry's secret power is Love?" gone horribly, terribly, hilariously in the other direction. It's worth it if just to get to the part where Luna tries to explain sexual intercourse.
8. Fandom Category: Harry Potter
Pairing: Harry/Hermione, Ron/Hermione, Harry/Ginny
Fic Title: Heart Shaped World
Rating/Warning(s): PG; spoilers for book 7.
Genre: Angst, romance, friendship, au.
Why This Must Be Read: Probably one of the most brutally haunting stories I've ever read. The last line of Hermione's last letter still has the ability to make my chest tight and to make me hurt for all of these characters and the what-might-have-beens. All of Parker's fic is beautifully written, but this is the one that I love and hate in equal measures and is one I just can't forget.
9. Fandom Category: Harry Potter
Fic Title: Revelation In An Invisibility Cloak
Genre: Smut, friendship, romance.
Why This Must Be Read: GUH. This is incredibly, incredibly hot, but it's also an incredibly plausible AU. Mostly though, this is just phenomenal smut that changes from hate sex to loving to fucking on a dime and does it beautifully.
10. Fandom Category: Harry Potter
Fic Title: More Equal Than You Know
Author: Obsidian Warlock
Rating/Warning(s): NC-17; dark themes, underage sexy-time, violence. Additionally, this is undergoing a rewrite, so chapter styles don't 100% match.
Genre: Suspense, Action/Adventure, romance, friendship.
Why This Must Be Read: The writing. 100%, the writing in this story is just phenomenally good. Obsidian Warlock is one of best and most readable authors I've ever encountered, and this is his opus. Not only is this story incredibly gripping, it's also an amazing look at what the series might have been, had it not been billed as a children's series. Moreover, it goes out of its way to make the characters actions and choices make sense, and it does it by organic and natural character growth. Basically, you get the reasoning behind people's choices and good lord is it amazing.