40 Fanfic Ideas That Work in Any Fandom, Plus How to Test Them

TL;DR: The fanfic ideas that land start from a relationship readers already love and change one thing about it. In Fansplaining’s 2016 survey of 7,610 fic readers, friends to lovers led all 144 tropes and enemies to lovers came 20th. Below are 40 premises sorted by mood, ship and length, plus a free way to test one in seconds.

Most fanfic ideas lists hand you a wall of prompts and no way to tell which ones readers want. The ideas that work start from a relationship people already love, then change one thing about it.

That relationship is usually not the one the lists push. In Fansplaining’s 2016 reader survey, friends to lovers led the most-loved list of 144 tropes and themes, and enemies to lovers came 20th. Canon-divergent AUs, where one small change rewrites what happens, ranked second.

A newer data point agrees on what fans come for. A 2024 Aarhus University study of 254,385 fics on AO3 (Archive of Our Own) found that fan fiction stays close to the original author’s style but puts less weight on plot and more on characters interacting.

The 40 fanfic ideas below are built on that pattern and sorted by mood, by ship and by length, so any two characters fit them.

My advice is to test an idea before you give it a month of evenings: paste it into the free AI fanfic generator and read the opening it writes in about ten seconds.

What Are Good Fanfic Ideas That Work in Any Fandom?

Good fanfic ideas for any fandom pair a mood with a relationship, so they fit whichever characters you choose.

The 25 below are grouped by mood, and each one works for rivals, partners, siblings or best friends.

Idea 6 is my favorite in the whole list, because it needs nothing from canon except two people who are bad at talking.

Mood matters as much as premise: Fansplaining’s survey found fluff the most-liked tone, angst a close second, and darkfic the least liked by far.

Fluff and Cozy Fanfic Ideas

1. The Snow Day Inventory. A storm shuts everyone in, and two characters are stuck counting the storeroom before morning. Every box they open holds something the other one hid there years ago.
2. Wrong Door, Every Time. One character has delivered a parcel to the wrong door every week for a month, on purpose. The person behind the door has been keeping a list.
3. The Smudged Recipe. A character inherits a handwritten recipe with one ingredient smudged away. The only person who might remember it is someone they stopped speaking to years ago.
4. Swimming Lessons. The most capable person in the group cannot swim. The least capable one offers to teach them before the trip to the lake, and nobody else is allowed to know.
5. The Spare Key. Two neighbors keep a spare key for each other for emergencies and have never had one. Then one of them gets sick.

Angst and Hurt/Comfort Fanfic Ideas

What is hurt/comfort: A fic where one character is hurt, physically or emotionally, and another looks after them. The hurt drives the plot and the comfort is the payoff.

6. The Unclaimed Funeral. Only two people come to bury someone everyone else forgot, and each assumes the other was family. Neither was, and neither leaves.
7. The Letters That Never Went Out. After a battle, one character finds a box of unsent letters addressed to them. The newest is dated the night before.
8. Taking the Blame. One character takes the fall for the other’s mistake and never mentions it. The other finds out a year later from a stranger.
9. The Day Before It Happened. Write the 24 hours before canon’s worst event from the side character nobody follows. The reader knows what is coming, and the character does not.
10. Fever Watch. One character sits up all night with the other’s fever and says everything they would never say to someone awake. In the morning, the patient remembers one sentence.

Alternate Universe Fanfic Ideas

What is a canon-divergent AU: A story that follows canon until one event goes differently, then follows the new path. It keeps the characters you know and changes what happens to them.

11. One Small Change. Pick the decision your canon hinges on and flip it. Then follow who lives, who leaves and who never meets.
12. Same Cast, Wrong Jobs. Swap everyone’s role. The villain runs the bakery the hero visits every morning, and the hero is the health inspector.
13. The Museum After Hours. The cast works the night shift at a museum where one exhibit moves whenever nobody is looking.
14. The Exchange Term. Two characters from rival schools, kingdoms or crews swap places for a term and have to live each other’s lives.
15. The Inn at the Border. The whole cast is stuck in a small inn on a closed border until the pass reopens. Nobody can leave, and somebody is lying about why they came.

Comedy and Crack Fanfic Ideas

16. The Group Chat Leak. Someone adds the wrong person to the group chat. That person has been reading everything for three days and finally replies.
17. Wedding Planners by Force. The two least romantic characters must plan someone else’s wedding on no budget.
18. The Secret Pet. A stray cat has lived at headquarters for a week, and every character has been feeding it in secret.
19. Undercover as Normal. The most dangerous character goes undercover as an office worker and is terrible at being ordinary.
20. Customer Service. The villain calls the hero’s help line with a genuine complaint. The call is recorded for training purposes.

Adventure and Mystery Fanfic Ideas

21. The Map Was Wrong. A wrong turn strands two characters far from home, and the only way back runs through the town one of them fled.
22. The Locked Room at the Reunion. Something goes missing during a reunion dinner, and every guest had a reason to take it.
23. The Lighthouse Logbook. Two characters keep a lighthouse for one night and find a logbook whose last entry is in one of their handwriting.
24. The Three-Day Blackout. A citywide power cut lasts three days, and the cast has to run everything by candlelight while tempers fray.
25. The Second Ticket. A character finds a train ticket in their coat for a trip they never booked, dated next week.

What Are Good Fanfic Ideas for Your Ship?

The best fanfic ideas for a ship start from a trope readers already love, then add one fresh obstacle.

Friends to lovers led Fansplaining’s survey and being isolated or trapped together ranked 13th, so those make the safest foundations.

Friends to lovers is the trope I hand to anyone who asks where to start. I don’t buy the idea that enemies to lovers is the safe pick, since it ranked 20th, behind quieter tropes.

Twentieth out of 144 still sits in the top seventh, so the trope has a real audience, and friends to lovers has a bigger one.

Ranks come from Fansplaining’s 2016 survey of 7,610 fanfic readers, who rated 144 tropes and themes. The top ten and what each trope means are in fanfic tropes explained.

26. Friends to lovers: The Award Speech. One friend has to write a speech about the other for an award night and realizes every story in it is about the two of them.
27. Slow burn: The Nightly Report. Two characters trade one-line reports at the end of every shift for a year. The lines get longer.
28. Trapped together: The Last Room. A snowstorm, one inn, one room left, and two people who have been very polite to each other for far too long.
29. Fake dating: The Plus-One Contract. Two characters fake a relationship for one family weekend, and the family likes the fake partner better than their own relative.
30. Enemies to lovers: The Same Blackmailer. Two rivals learn they are being blackmailed by the same person and have one week to work together.
31. Soulmate AU: The Word on Your Wrist. Everyone is born with the first word their soulmate will say to them. One character’s word is “no”.
32. Found family: The Holiday Nobody Planned. Four characters with nowhere to go end up at the same table, and by midnight it is a tradition.

A recent r/FanFiction thread on favorite niche tropes leans toward quieter material. Its picks include mourning and the comfort after it, storms and power cuts handled for real, accidental journeys, and a platonic bond the ship has to make room for. Ideas 6, 21 and 24 above are built on that list.

What Are Good X Reader Fanfic Ideas?

What is x reader: Fan fiction written in second person, where “you” are paired with or befriend a canon character.

Good x reader fanfic ideas give “you” a clear role in the scene, so the reader steps into a part instead of watching.

A job, a home or a problem to solve does that work better than a description of how you look.

33. The New Recruit. You join the team on your first day, so every introduction doubles as a tour of the world.
34. The Neighbor’s Mail. You keep getting a character’s mail, and they keep knocking to collect it, each time with a worse excuse.

I would drop the Y/N placeholder entirely and write around the name. The same habit causes trouble in Character AI chats, where Y/N reads like a clumsy insert and the bot can treat it as a separate character.

What Are Good Short and Long Fanfic Ideas?

Short fanfic ideas need one moment and one change, while long fanfic ideas need a question that takes months to answer.

Match the idea to the length before you start, because a good drabble premise stretched to ten chapters goes thin.

Drabbles are the format I reach for when an idea is good but small. A long fic earns its length only when the characters need time to change.

Drabble and 221B Ideas

A classic drabble is exactly 100 words. A 221B comes from the BBC Sherlock fandom, where each story must be 221 words long and end on a word that starts with B, according to Fansplaining.

35. The Knock. One character, one door, and the hundred words before they decide to knock.
36. Notes on the Fridge. A 221B told only in notes two roommates leave on the fridge because they never see each other, ending on the word “breakfast”.

Dialogue Prompts for a One-Shot

An opening line can carry a whole one-shot when it implies a history. These two also work as AI roleplay prompts if you would rather play the scene out first.

37. “You kept it? I told you to throw that away years ago.”
38. “Don’t panic. I need you to pretend you’ve known me for ten years.”

5+1 and Long Fic Ideas

What is a 5+1 fic: A story told as five times something happened and one time it went differently. The sixth scene is the payoff.

The structure bends easily, and 4+1, 3+1 and 1+5 versions are common.

39. 5+1: Five Times They Almost Said It. Five times one character nearly confesses and backs out, and the one time they do not need to, because the other says it first.
40. The Year After. A twelve-chapter long fic set in the year after canon ends, one chapter per month, each from a different character’s point of view.

How Do You Come Up With Your Own Fanfic Ideas?

Your own fanfic ideas come from one gap in canon plus one relationship you want to see under pressure.

Fix-its, missing scenes, side characters and point of view shifts are all reader favorites, so canon’s gaps are the richest place to look.

In Fansplaining’s reader survey, fix-it fics ranked 12th, missing scenes 14th, minor character focus 32nd and point of view shifts 34th, all inside the top quarter of 144.

The rule I follow is a shared room and clashing wants, which fits the Aarhus finding that fan fiction leans on characters interacting more than on plot.

1. Find the gap. Pick a missing scene, a what-if, the months after the ending, or the view from a side character.
2. Pick the mood. Decide on fluff, angst, comedy or adventure before you plot, since the mood decides which scenes you need.
3. Borrow a plot from outside fandom. Rebecca W. Black’s 2009 study describes a fic that cast Cardcaptor Sakura characters in a plot loosely based on the movie You’ve Got Mail. Neighbor feuds, heist films and courtroom dramas lend structure the same way.
4. Keep a plot bunny list. Black’s paper defines a plot bunny as a story idea that multiplies into other ideas, so write each one down the moment it arrives.
5. Test the premise. Draft the opening scene fast and read it cold, as the next section shows.
6. Post it free. AO3’s parent nonprofit holds on its FAQ that fan works are legal under US fair use. It says commercial fan works can be fair use too, but its defense work covers noncommercial ones.

If you want someone else to set the prompt, October challenges such as Whumptober and AU months like AUgust hand out a prompt list for the whole month.

How Do You Test a Fanfic Idea Before Writing It?

Testing a fanfic idea means drafting its opening fast and reading it cold.

The free AI fanfic generator writes about 450 words in roughly ten seconds, which is enough to see whether a premise has a scene in it.

Fans already try characters out with AI. Researchers Owen Lee and Kenneth Joseph found in their study of Character.AI bots that roughly one in four of 2.1 million greetings is tied to a fandom.

Some bots read like fanfiction, for better or worse.

I treat the generated draft as a sketch for judging the idea, and then I write the fic myself. The difference between a vague idea and a testable one is specific people, a place and a problem.

Before: “Sherlock and John at a funeral”

After: “Nobody comes to the funeral of an old landlady except Sherlock and John, and each assumes the other must be family. Neither knew her well.”

With that idea and the settings Hurt/Comfort, Bittersweet, third person, General audiences and Short, the generator returned a 451-word opening called “The Unmarked Stone” in about 11 seconds.

Its first line was strong: “The vicar’s voice cracked on the third hymn, and Sherlock knew he was performing sincerity rather than feeling it.”

It also slipped. It introduced “the woman in the black coat” with “young shoulders, military posture” and then revealed her as John, the kind of continuity error you fix by hand.

The generator held its premise better on a Pride and Prejudice idea, in which Elizabeth and Darcy are the only two who know where Netherfield’s spare candles are kept.

It came back as a 429-word scene with Darcy insisting, “I make it a habit to familiarize myself with the layout of any house where I am staying.”

The generator also has a continue button, so a premise that works can run a second scene before you decide. For original fiction with no fandom, the AI story generator works the same way.

Pick one idea from the 40 above, run it with the matching settings, and keep it only if the opening already holds a scene you want to finish.

Quick Takeaways

• Start from a relationship readers already love: friends to lovers led a 7,610-reader survey, and enemies to lovers came 20th.
• Canon’s gaps make the strongest ideas, since fix-its, missing scenes, side characters and point of view shifts all ranked in the survey’s top quarter.
• Match the idea to its length: one moment for a drabble, one long question for a multi-chapter fic.
• Test a premise by drafting its opening in the free AI fanfic generator, then write the fic in your own words.