The New Romance
(Alternatively: protagonist-centric adventure stories with little or no romance as requested by @exocara
Harry Potter
The Bitter Hug of Mortality by She Who Cannot Be Turned
Type: staring into the abyss
https://www.fanfiction.net/s/10502653/1/The-Bitter-Hug-of-Mortality
Harry is the younger brother of the Boy Who Lived and is a little strange. He hears voices no one else can hear, he knows things no one else should know and he's just this side of crazy. Oh, and everyone thinks he's a squib. When it comes to Harry, however, all bets are off and nothing is entirely certain.
Sisphyus by esama
Type: Groundhog Day
http://archiveofourown.org/works/1113651
Harry gets another chance - and another and another. At some point, they stop feeling like chances at all.
Petrichor by BlameMyMuses
Type: staring into the abyss
http://archiveofourown.org/works/690222
In attempting to stop Sirius from falling through the Veil in the Department of Mysteries, Harry goes half through it himself before being dragged back into the living world. After the battle, things should have gone back to normal...but they don't. Something about Harry is changing, and he doesn't know why, what to do about it, or just what it means for his future confrontations with Voldemort.
Art of War by Wendy Ginny Greenleaf
Type: rewrite
https://www.fanfiction.net/s/10179471/1/Art-of-War
OoTP. Harry, Ron and Hermione realize that they're going to have to save their own lives - because no one else will. Turning to their own war plans, they create an inner circle and begin recruiting assassin, spies, ticking time bombs. A group of rag tag students will become an army. Can this give Harry the opening to defeat the Dark Lord? Inspired by Red Dawn.
KHR
The Sky and his Sun by Adriana Espan
Type: can be read as non-romantic
https://www.fanfiction.net/s/10640799/1/The-Sky-and-his-Sun
Where Tsuna is the Sky Arcobaleno, and sky arcobalenos look like teenagers who don't age or die. He is not the Vongola Decimo. The question is, if Tsuna and Reborn were together in the past, why did they decide to part ways after becoming Arcobalenos? R27/slight All27. AU. Follows canon's plot but will skip the parts that are deemed as unnecessary.
A Sky Full of Stars by ArielLux
Type: AU
https://www.fanfiction.net/s/11567751/2/A-Sky-Full-of-Stars
At the age of seven, Tsuna met a green magical chameleon. At eight, she dreamt of 'kufufu'ing pineapples. At nine, a shark bought her a cake, after he almost cuts her head off. At ten she found out her father's real work, then, at twelve, a baby with a black fedora proclaimed that she was the heir of a powerful mafia Famiglia. Oh, and wasn't that her Magical Chameleon? Fem!27.
We Weren’t Born to Follow by Seito
Type: i have no idea (im so sorry)
https://www.fanfiction.net/s/11274899/1/We-Weren-t-Born-to-Follow
"Don't walk behind me; I may not lead. Don't walk in front of me; I may not follow. Just walk beside me and be my friend." In which Ienari was picked to be Decimo instead of Tsuna, but that's okay because Tsuna was always destined for bigger things than being a mafioso. Twin!Fic. Eventual R27
Wide Skies (Stage One) by Lector Dominion
Type: supportive twins
https://www.fanfiction.net/s/10712305/1/Wide-Skies-Stage-One
Sawada Iemitsu left the Sawada household for work, leaving his lovely, loving yet airheaded wife and three brilliant kids behind. He returned to their home with Reborn years later, only to discover that his wife became distant with him, and his three kids became two teens. Stage One of Wide Skies.
KnB
The (In)Sanity of the GOM by misminor
Type: GOM dynamics (aka: is this space jam)
https://www.fanfiction.net/s/8565182/1/The-In-Sanity-of-the-GoM
In which Kuroko makes Akashi proud. The high school teams witness the dynamics of the famed GoM. And Seirin thought Kuroko was the normal one. A series of (possibly) unrelated one-shots/drabbles. (writer previously known as "psychotic luv")
A Single Step, A Thousand Miles by cywscross
Type: character exploration
https://www.fanfiction.net/s/9294997/1/A-Single-Step-A-Thousand-Miles
When Tetsuya first arrives at Seirin, it's the start of something he's never had, and for the life of him, he can see no end.
Pretenders by Green Priestess
Type: AU
https://www.fanfiction.net/s/11522235/1/Pretenders
AU. Due to Kuroko being a girl, she never knew or met the GoM and she's in a different school. And Kise met her at Streetball. It seems they're still destined to be a teacher-student in Basketball no matter how different life is. Then Kise asks for a very unusual favor. Fem!Kuroko Skilled-but-weak!Kuroko
Redoubled Peonies by Branch
[Additionally: Walk Through the Valley of Lilies, series]
Type: character exploration
https://archiveofourown.org/works/522941
Imayoshi decides to return Riko's favor by throwing Aomine, Kuroko, and Kagami together in a match. It's a different kind of revelation for each of them.
Assassination Classroom
Judecca by Adamant
Type: character exploration
https://www.fanfiction.net/s/9483224/1/Judecca
A collection of interconnected drabbles and short stories exploring the extensive cast of Assassination Classroom, and telling the story of their development with a slightly darker twist. AU starting with manga chapter 163. ToC in the first chapter.
We failed Once by Antartique
Type: time travel
http://archiveofourown.org/works/4364723
They wake up, their memories scrambled, their bodies wounded where they shouldn't. The moon is whole. The year is 2014, two years before it was a day ago. Everything is confusing, but there is one thing they know: we failed once, we will not fail again. But, how many people can they save if they can't even save themselves?
Or: the world ends and the clock ticks back. Four children and an AI are sent back to the start. This is their tale of struggles and discovering their true purpose in life, even if that purpose may be killing all those who ruined their old lives.
The Flower Game by souja
Type: the higher you fly, the harder you fall
http://archiveofourown.org/works/2813732
Korosensei thinks flowers are beautiful
Natsume Yuujinchou
The Human Mask by harunekonya
Type; Natsume becomes a god
https://www.fanfiction.net/s/7731108/1/The-Human-Mask
Sequel to Worthy of a Name. Natsume slowly learns to deal with life as a god. An inter-connected vignette series. Gen.
Finding Home by darkcyan
Type: the end is here
https://archiveofourown.org/works/1613045
On a school trip, between one moment and the next, Tanuma's teacher and about half of his classmates disappear. Everyone must figure out how to deal with this changed world, and the new dangers it has brought with it. Meanwhile, Tanuma wants to believe that Natsume was not one of those who disappeared that day ... but if not, where is he?
Natsume Takako no Yuujincho by Fiametta1808
Type: rewrite
https://www.fanfiction.net/s/8397101/1/Natsume-Takako-no-Yuujincho
Meet Takako, an average sixteen-year-old high schooler with an unusually fat cat, a Book containing what is effectively her own demon army, and secrets about her past that can only be revealed by speaking to spirits. And that's not even considering the number of exorcist families who are chasing after her... AU!