The best I've seen (check my Kiyo Tier list for some of these):
Ichika Amasawa from... anything basically. Of the top of my head, Haunted by the Past, The Eroge, The little devil of the 5th generation, and Married non Lovers
Siesta from both Detective of the elite and especially Classroom of the Elite: Quintuplets, both by derpycote
Minami Nanami from Top-Tier Character Ayanokōji-kun by juli0os
Aoi Hinami from Top-Tier Character Ayanokōji-kun by juli0os
Miura Yumiko from He Will Be Mine | Ayanokouji x Fem!OC [Reincarnated in COTE]. by Kiyone-Chan
Himiko Toga from Ayanokouji: Free Life by angle99999
Other Dimension Kiyone Ayanokouji from... idk. WHY WAS Forget Me Not DELETED?!!!! I may be wrong about the name, and this may be the name for the WR Female OC fic my picture comes from, BUT WHATEVER! BRING IT ALL BACK😭
Shinohara from Classroom of the Elite Unexpected Tool by KingpinRisette
Wang Mei-Yu from Different Heroine (V1) by brian744
Kiyotaka's (non-canon) caring mother. I forget the fic name, but she started teaching his Class D, and he walked out in protest after 5 minutes.
Hiyori Shiina in The Angel from Another Class is Rotten, but I'm Interested in Her by RainSennin (pretty new, updating, AND PRETTY AWESOME! She even unlocked a certain part of Devilkouji in the very "first" chapter!)
Any cold, but not emotionless Kiyotaka fics (like in The Angel from another class is rotten; Cold Eyes; Heartless Masterpiece, please mention more 🙏)
Arisu Sakayanagi from anywhere practically... especially when she's active or around Kiyo for extended periods of time. The way she was used in both the MHA Free Life and also the Overlord crossover: COTE and New World (deleted story formerly by 1Arisu2, being redone by 1Deathdeath2) stick out... along with The Eroge...
Suzuki Shizuku from White Room Masterpiece : The Reaction. Shoutout ejjs27, the creator of this inspirational OC!
The Eroge... everyone?
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My Wishlist (please comment fics that fit!):
More Ichika Amasawa
More Siesta
More Ryu Lion (Danmachi)
More cold but discreet Kiyo fics, kind of like Cold Eyes and Heartless Masterpiece (I personally dislike "all out" kiyo fics where he exposes himself like Kouenji)
More WR Yuki (she's basically Suzuki Shizuku except canon, shoutout Liquid Inspiration!)
More capable OC's like Miura Yumiko in He will be mine, or other WR/traumatized students he can relate to/share pain with
More Married But Not Lovers crossover. The great anime/manga is called Fuufu Ijou; fanfic COTE: Married Couples, but not Lovers by derpycote experiments with this (it gets mature and explicit)
More personal interaction with Manabu Horikita. I just got this idea while reading My Peaceful Life: Fantasy Edition. Dang, honestly, he's legit the only respectable guy who could even be a good MC w/o being ooc, besides maybe Akibro and Kanzaki...
Side note, every time there's a female Kiyo fic, I usually stray away from them because I feel like : MAN, there's no respectable men who'd deserve or would fit with someone like her without making them ooc... except Manabu. Then again some fics make Ibuki, Manabe, and the aforementioned Shinohara lovable, so I guess authors could do that to the Ryuens, Kanzakis, Hashimotos, and Koenjis of the world. It would be a Kiyo Tier challenge tho
The Kazami Siblings (from The Grisaia series)
Fruit of Grisaia (Kiyotaka's dilemma and Fruit of the Elite seem discontinued)
More Danmach. I know integrating, genocidal masterpiece, an older but probably deleted RyuxKiyo fic, and The Perfect Human in a Fantasy World. I love the concept of his martial arts putting him at level 3 difficulty at weakest, and having spells/power influenced by the White Room
A colder/scheming/more active/Kiyo-like Chiaki Matsushita. For example, Cold Eyes, where she was amazing! Having her as another partner like Kei, or even as a romantic partner feels very great in many fics. Heck, thanks to Volume 0's implications, she could have knowledge of Atsuomi like Kanzaki (and probably Kouenji))
Arisu Sakayanagi in a crisis (like in Apocalypse, OR in a fantasy where she's able-bodied, like in cote and new world and Mha Free Life
Chelsea from Akame Ga Kill, or X Akame... or Esdeath, ...... or Kurome, ............ or Najen.. holy Haruki! THIS SHOW WAS LOADED! It got me thinking: Sheele is their Airi Sakura, except WAY more believable AND beloved ☺️
Akame Ga Kill in general
More RWBY. There are 2 that I know: COTE X RWBY [Ayanokouji, Amasawa, Ryuen, Albert]; by Kiyone-chan and Classroom Of The Elite/RWBY: The Lone Shadow) by Ballislife2310
An Arisu that rivals Kiyo in EVERY way. YES I KNOW her impairment and personality makes her aura and actions feel SO much more impactful than they ought to. She's practically perfect the way she is at entertaining us readers! I get it completely! I hate bringing this up, hence it's near the bottom. Occasionally, I just imagine her being the literal whole package, same personality, height, looks, intelligence, and basically the opposite physical strength in canon to darn near be 1B to Kiyotaka (if not better😏))
Got this idea mainly from the deleted fic Cote and New World. Kiyo cured Arisu's disease so she could move normally, level up, and kick but! She gave a VERY fitting, heartwarming reaction I would like to see more of (not to mention the way she went about their WHOLESOME interactions afterwards)
Ami from Toradora (either or could be Isekai'd)
Fics like Time-Leap into a Promise by Adisial-Sensei (shout out to Sensei!!!)
Isana Higashira (from ex step sister... I stopped watching the anime after they awkwardly rushed to friend-zone her... I'm annoyed by practically everyone except her and the male mc. She's funny, even with the little screen time afterwards. She don't understand personal space (including with her assets). She's like a tomboy Hiyori... oh lord, she's more like Ichinose and Hiyori combined 😏)
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Fics I may one day make time to read:
Re Zero (the long crossover)
Free Will (I'm at VIP exam start)
Checkmate
Self Test
Man On a Mission
The Odd One Out (1 and 2)
Beast of the Black Room
Itachi of the Elite
Liquid Inspiration (I'm at the very beginning of ANHS)
More with Karma Akabane
More Fics that give Kiyo more WR informed allies/rivals/enemies, etc. Basically, more WR students like in Free Will. Maybe some will be bystanders trying to live a peaceful life.
More White room exposed fics. Timing doesn't really matter. Although, doing it in the middle of their graduation ceremony as Kiyo does NOT graduate Class A (he'll poetically switch to Class D right before it's over) would be INSANE! I would love to see everyone's reaction, especially Suzune's Class A going from celebratory to empty, after realizing that their pains pale in comparison to his upbringing. That realization.... I may be a sadist
Afterwards, a lot of people like Manabu would try to in some way defeat Atsuomi and Co. or at least take Kiyo back, almost like in Time-Leap into a Promise by Adisial-Sensei. Take whatever parts of this idea you want. Just make sure the newly informed feel the weight of a T-Rex
Prepared
Shinji's Playground (in fanfiction.net)
That "Kiyo has Amnesia" fic (Mei-Yu was a major character)
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Random ideas:
Yooo, I just thought of this before posting the fic. What about Kiyo switching years using private points to try and stay in high school forever?
Code Geass (Maybe X CC or Kallen)
Kyoko Kirigiri (DanganRonpa)
Revi/Black Lagoon
Vegeta's 2nd Rival ... or a long lost ex-rival, idk. Or Kiyo could be Broly to him, and Team Four Star would come out of retirement to animate it
Teenage Mandy from the Grim Adventures of Billy and Mandy
Ruti from that banished to countryside fantasy (Yes, I'm reading and enjoying My Peaceful Life: Fantasy Edition)
Arifureta (sub for Hajime or just put ANHS in, lol)
Vergil from Devil May Cry... in whatever way... have them fight somehow.. u know the tune deep within (heh heh, V vs X)
Ladies Vs Butlers (I'm practically thinking of The Eroge fanfic, but in that world. On the same level, a Tomomi Saikyō X Kiyo could be a great fit!
That glasses brunette girl from... idk, some rom com with a love pentagon between male mc and his best male friend, and 3 other girls, 2 liking the best friend, best friend likes glasses girl, glasses girl... that's enough! COULD SOMEONE NAME DROP PLEASE? I'm too lazy to research the name further 🤣.
Trinity seven (Would hate to rid Arata. He's goated)
Rascal bunnygirl
Yamada and 7 witches
Kokoro Connect (basically any "switch bodies with kiyo" action lol)
Tokyo Revengers (I've only seen like 3 minutes of the Black AirForce Energy video. Will eventually watch the actual anime)
Tower of God (with less characters hopefully)
Atsuomi vs ANHS ... with or without Kiyo. Imagine the Sakayanagis, Kouenjis, Kanzakis, Matsushitas, Horikitas, Amasawas, and other powerful factions team up to take down Kiyopapa's gang! Or, Kiyo with Arisu's cane could go to town...
RWBY, except put him in KCAL from TommyLau's 30 days RWBY animation (have Kiyo interact with a sightly crazy Angel often. That would be INSANE... and there's only a decent reaction fic to the Angel animation, sadly. Additionally, it seems like they are huntsmen who hunt huntsman, almost like mercenaries... and yes, in the original Lee animation, LEE KILLED RUBY IN THAT FINAL ATTACK! Just so you know the demeanor, the nature of the group. Kiyopon totally can't fit in... right?)
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Conclusion:
I'm just throwing my imagination at a screen here. It's been like 4 days total I've written this. Honestly, proofreading has taken the most time. I've definitely missed some fics, especially since I've been around since 2021-ish, reading some of those first reaction fics (uggggh, remembering those boring bus scenes, annoying Kanzaki tropes, and copy cats... 🤢).
I hope to inspire others with fun ideas for fanfics, shoutout some great fics, and just stir some conversation.
Side note: Future fanfics will be wild, especially with the inevitable Ecchinose ntr'ing probably coming soon (not confirmed or canon). I wonder what Kiyo's emotions will be if he tries to breakup with Kei (again, not confirmed or canon). Kiyogod could also be lying to us in his head for the 401st time 🤷
Speaking of Honami, her character 180 is WILD! I may talk about it in the future, but I'll just say: in this cutthroat environment, I can REALLY get behind and like her now! There's nothing like someone who knows what they want, and commits to grab what they want unapologetically. Haruka and Arisu were right: NOBODY can be pure ALL of the time.
Back on topic, one day, I may actually publish a fic. Matter of fact, I meant to publish one on 2023 new years, til I read it.... Maaaan, I'm starting to understand how author's feel when they say, "Oh, my writing sucks! I may rewrite! Cringe," even though reader me feels very entertained by their writing most of the time!
I'm trying to write what I'd want to read, and I am still missing the feel I want to feel from the scene. I've made some drafts and edits (on and off timewise), and plan to make more. You know what, scratch that! I'll come out with it soon. It will be like me irl: I do my best proofreading after I hit send 👍!!!
My main idea is: making scenes I want(ed) to see, including ones in other fanfics. We've all experienced the dreaded Discontinue/Hiatus curses, but hey, the point of fanfics is to make fiction reality (fiction)!
Thank you all for reading! Please comment aplenty, let other people know, and vote!