Most of the fics listed here will be from Video games, ranging from het to slash pairings. Most fics will probably be romance in nature, but you may see a general fanfic here and there. I'll also put warnings/rating based on Ao3's system, since most fics will be on Ao3. Also, most fics will be full of spoilers, so keep that in mind.
I'll also be adding to this over time. I may review a few of these fics in the future (More so Fire Emblem since that's the fandom I actively read for now).
Fics by Shinoochi in general. Instead of listing basically all this person's work, I'm just going to recommend them here. Shinoochi writes about various pairings while staying true to the characters. Below are my personal favorite works. I'd highly suggest reading their Noiz/Aoba pieces if you like that pairing.
All of You (Noiz/Aoba, E) - Great smut piece featuring this pairing with a very interesting premise. Wonderfully IC as well. If you're on the fence on this pairing, I'd recommend this. If you already like this pairing, this will crave your itch. Spoilers for Reconnect good end as well.
Warmth in Your Hands (Koujaku/Aoba, E) - Another great smut piece by the same author as above. It's some domestic fluff after Reconnect, but I think you're good even if you didn't read it.
As a fair warning, most of these fics are based on the VN, and not the anime.
Again, reccing an author. Calenlass Greenleaf writes pretty amazing fics with various pairings and various ratings. I'm going to take three fics that I thought were really written well, but I recommend checking out their other works.
What is Enough (Souji/Chizuru, E) - First time fic featuring this pairing. Very sweet and stays true to both characters. The summary pretty much sums up WHY I like this fic, because that's how I view the pairing.
Again (Hijikata/Chizuru, M) - I normally don't like this pairing too much, but it's very well written here. This story is somewhat an AU and spoils the prequel to Hakuoki, but you should be fine, even without reading the prequel.
It's Always the Quiet Ones (Saito/Chizuru, E) - Cute fluffy smut taking place at the end of Zuisouroku/Memories of Love epilogue. There's spoilers for MoL (PS3 version of Hakuoki). Very in character fluff with a dash of smut.
Final Fantasy 7
And again, recommending an author. Miko writes some really fantastic pieces that take place in the FF7 universe. Most of them pre-date AC and CC, so be warned.
Too Good to be True (Zack/Cloud, E) (Review here) - I already said everything I wanted to say in the review. Again, I'll say this is the fic that made me ship this pairing. If you're on the fence with this pairing, read this one. It's remarkably in character and actually treats the female counter-parts with the due respect they deserve.
Permission to Touch (Zack/Cloud, side mentions of Zack/Aerith, E) - This is not only funny in the best of ways, but features cross-dressing Cloud. And some well written smut. If you're looking for a humor piece, you'll get your fix here. Predates CC, so non canon to it, if you're picky about that.
Blood of the Innocents (See review here) (Zack/Cloud, one sided Sephiroth/Zack, verious others, M, take note of warnings in the review) - This fic is a perfect example of how an AU fic should be written, though it runs more like a Butterfly effect AU. Spoils the entire game.
Still Waters (See review here) (F!Souji/Yosuke, many one sided F!Souji pairings, E) - A gender swapped Main Character in the Persona 4 universe with a catch, the MC is a blank state, literally. Has some really great build up. Spoilers for the entire game.
Groundhog Day Effect (Souji/Yosuke, E) - Souji and Yosuke get stuck in a time loop. I recommend this one mostly because it has very decent build up compared to the many Souji/Yosuke fics I've read, in general. If you're looking for that with some fluff and angst and smut mixed in, this is a good fic to go for.
Fire Emblem: Awakening
Restless Nights (Chrom/F!Robin, E) Hurt/Comfort fic featuring Chrom and F!Robin. Angst and smut, just the right combination. There's massive spoilers for the game, so be warned.
Fire Emblem: Fates
Coronation (Xander/F!Corrin, T) - Very well written build up fic featuring Xander and F!Corrin. There's massive spoilers for the Conquest route. Plus the story uses Xander's japanese name (Marx) and it also uses a fixed name rather than Corrin. It's still really well written, probably one of the better fics for this pairing. This is one in a series of 3 fics, but I haven't read the others.
His Thoughts (Takumi/F!Corrin, T) - It's Takumi angst, enough said. It also has it's fluffy moments. It's short, but sweet.
(you are)(like a malestrom) (Takumi/F!Corrin, T, boarderline M) - There is a TON of sexual tension and of course, angst in this piece. I was skeptical reading it since it was pre-release of the actual game, but it's somewhat in character if you look at this after their A support.
Breath of Life (Leo/F!Corrin, small references to Camilla/Takumi, T) - I'll admit, I'm not really fond of this pairing, but this fic is well written and has some excellent build up for it. Spoilers for Revelations route up to chapter 17.
The Light is You (Leo/Takumi, E) - Very sensual pieces featuring this pairing with a dash of smut. This somewhat spoils their S support and Revelations, so be warned.
If You Could Just Forgive Yourself (Leo/Takumi, T) - Excellently well written build up following their Revelations support, but doesn't really follow Revelations. If you're unsure of this pairing, I'd recommend this piece to read.
Pawn to E4 (Leo/Takumi, T) - Decent build up fic, but not as good as the one above. Focuses a lot on Leo and his angst post Birthright, which I liked the most of this story, since a lot of fics tend to focus more on Takumi angst. Massive spoilers for Birthright route.
And Whatever Differences Our Lives Have Been, Together We Make a Limb (Leo/Takumi, T) - I don't usually recommend unfinished works (And holy shit, this title is long), but I was really shocked I liked this fic. It's an AU where Takumi and Leo are forced into an arranged marriage for politics.
For Your Eyes Only (Leo/Takumi, part 1 T, part 2 M) - A two part series that takes a very interesting premise. Takumi was born blind and the way he sees is through the Fujin Yumi. This has massive spoilers for Revelation and their support. Part 1 is build up fic, part 2 is pretty much flangsty smut.
Reflection (Leo/Takumi, T) - Takumi gets badly injured and Leo blames himself. The one interesting premise is that this is told from Sakura's PoV.
Give Corrin a Break (Leo/Takumi, first part T, second part E) - I'm really only recommending this because this is a really funny story. Corrin forcefully plays matchmaker between her two clueless brothers.
Incandescence (Leo/Takumi, M) - Another sensual piece where Leo's favorite passtime is painting and his new target is a certain Prince. There's no build up here, but I liked the overall idea of the fic. It also has a nice piece of fanart in the fic as well.
to a place where no one's seen us before (Leo/Takumi, E) - I put this with no capital letters because the fic does it too. Dunno why. I'm really only recommending this because the smut is really well written. And Takumi being Tsundere to the max.
Ferocity (Leo/Takumi, M) - This actually takes an idea that I haven't seen in any of the fics that I've read, the fact that Leo and Takumi have dragon blood running through their veins. And it goes as you may expect, considering the M rating. It's nothing too explicit. The second part is M!Corrin/Niles, which I did not read, just if you're wondering about the part 1 near the top.
The Boy I Like (Leo/Takumi, E) - The only reason I recommend this is because of Tsundere!Takumi and Leo being a smug bastard. This is how I like the pairing, to be honest, how their characters are in the game. Oh and Takumi dresses up in a Yukata.
Fool's Game (Leo/Takumi, E) - I think the tag perfectly describes why I like this fic, basically because they're both being smug assholes in this fic. And it's Hate sex, something that the fandom is surpringly lacking, considering the personality of these two.
I Fly on Crippled Wings (But I Will Take Your Bitterness Away) (Leo/Takumi, T) - The writing for this fic is so-so, but the idea really saves it (And has a very pretty fanart to the story as well). Basically, Leo is tasked to spying on Takumi through his dreams. The problem? Takumi has nothing but nightmares. This spoils a little of Revelation, but doesn't follow it completely.
The Poison Tree (Leo+Takumi, T) - This isn't a pairing fic really, but this is a real beautiful piece where Takumi can't tell the difference between his dreams and reality. It takes both Conquest and Birthright and takes a unique spin on the paths, so be warned for spoilers.
The Worth of Words (Leo/Takumi, G) - Pretty much pure fluff of Takumi and Leo talking about their feelings to each other.