What Is a Headcanon? Five Families, Three Questions, One Test

The question what is a headcanon usually gets an encyclopedia answer: a fan's personal addition to a story that the story never confirmed. That answer is true and it is useless, because it does not tell you which of the five sentences on your screen to keep. So this page answers it the other way round — as a test you can run in the time it takes to read one line of dialogue. Every number on it was counted out of the file that serves the generator on this site: a fixed bank of five families by six tones, 180 lines, all of them countable rather than taken on credit.

The bank matters because it makes the definition checkable. A headcanon is not defined by who wrote it or where you found it; it is defined by what it does to a character's behaviour. These 180 lines are unusually good material for showing that, because they were all written to one rule — each line makes exactly one claim about exactly one person and then stops. When you can see 180 of them side by side, the shape of the thing you are asking about stops being a mystery and becomes five families with a test attached to each one.

The test is a filter rather than a definition: two gates remove sentences that are not really yours to invent, and the last gate removes the ones that will not show up in a scene. The ordering matters — a sentence that fails gate two has already failed gate one, which is why an AU is never a headcanon by accident, and a sentence that fails only gate three is the most common thing people mistake for a headcanon.

Three questions, and the impostor each one removes

Each gate exists because a different kind of sentence keeps getting called a headcanon. Naming the impostors is most of the definition.

Gate one removes canon. If the source settles the sentence, you do not get to decide it, you get to look it up. Nothing about confidence changes this. Knowing a character's eye colour, their job, or the fact that their sister died is not a headcanon even if you had to hunt for it, because the answer exists outside your head and other people can check it. This gate is also the reason a headcanon is not the same thing as being right.

Gate two removes the AU and the fic. A headcanon fills a gap. The moment your sentence overwrites something the source settled, you are still writing something worth writing, but you have changed documents: from a reader's notes into an alternate version of the story. That is why the two failure modes are separated. "Their sister is alive" is not a bold headcanon; the source said otherwise, so it is a different timeline.

Gate three removes trivia. This is the gate most sentences fail, because it is the only one that asks about behaviour rather than about facts. Take the sentence "{name} has two brothers." It is not settled by any source, it contradicts nothing, and it is still not usable, because you cannot stage it. Now attach an action to it: "and calls the wrong name first when tired." You can stage that in one line of dialogue. Nothing about the two brothers changed; the sentence only became a headcanon when it started costing the character something measurable.

A fourth check is worth keeping separate, because it is not a gate but an inspection. Take your sentence, swap the character's name for a different character's name, and read it again. If it still sounds true, the sentence was never about your character — it was a description of a type. Every line in this site's bank passes that swap unchanged, deliberately, which is exactly the limitation described further down.

The five families, and the one question each answers

The bank on this site is not a pile of 180 interchangeable lines. It is five families of 36, and each family answers a different question about a person. The family names are Personality, Backstory, Relationships, Quirks and Secrets. Read as questions rather than as labels, they cover almost everything you need to know before writing a character into a scene:

• Personality — what are they like when it costs nothing? 36 lines. "{name} falls slowly, then all at once, and everyone around them notices months before they do." Its failure mode is a list of adjectives: kind, sharp, tired. Adjectives are not behaviours, so they cannot pass gate three on their own.
• Backstory — where did a habit come from? 36 lines. "{name} was banned from a family board game at twelve, and the ban was never formally lifted." Its failure mode is a biography. An event that never explains a present habit is a date in a timeline, not a headcanon.
• Relationships — who do they owe, and who keeps them honest? 36 lines. "{name} is the reason the group chat needed a second group chat." Its failure mode is inventing a second person the source never gave you, which is how gate two gets tripped without anyone noticing.
• Quirks — what do they do without noticing? 36 lines. "{name} carries a bag that contains everything except the one thing needed." Its failure mode is costume rather than action: a quirk you describe but never let interfere with anything is decoration.
• Secrets — what do they hold and not say? 36 lines. "{name} reads the instructions, throws them away, and then does it their own way out of pride." Its failure mode is a secret with no cost. If nobody can be hurt by keeping it, nobody can be moved by it being kept.

Each family is 36 lines because the bank is sorted twice: 36 is six tones times six lines. So the smallest slice you can ask a family for is one family in one tone, which is six alternative answers to that family's question. That is a useful size, because six candidates is enough to choose from and few enough to read in one sitting.

The families also have opening habits you can hear once you know to listen for them. Of the 36 Secrets lines, 17 begin the same way — the character's name, then has — which is what a secret is, grammatically: something a person holds. Backstory leans on the past, with was opening 8 of its 36 and learned opening 5. Quirks are the opposite: 36 lines spread across 31 different opening words, because a habit can be literally anything a body does. None of that decides which family a line belongs to. It only tells you what each family tends to sound like.

The five families are not in the words

The tempting way to sort a list of headcanons is by keyword, and it does not work. I went looking for five marker sets in the bank — words about origins, habitual words, concealment words, words naming another person, and judgement words — and only two of the five behave.

Words about where something came from (grew up, learned, was born, used to) appear in 24 of the 36 Backstory lines and in only 3 to 8 lines of each other family. Words naming another person (friend, sister, boss, crew) appear in 9 of the 36 Relationships lines and in none of the Quirks or Secrets lines. Those two are tells. The other three marker sets are shared evenly enough across the families to be worthless as labels.

The bigger number is the one worth remembering: 71 of the 180 lines match none of the five marker sets at all — 20 of the 36 Secrets lines, 18 of 36 Quirks, 16 of 36 Personality, 14 of 36 Relationships, and only 3 of 36 Backstory. Almost two lines in five contain no signal word whatsoever, and they are spread across the families that people most often try to sort by vocabulary. This is the practical argument for the whole page: a family is a question the line answers, not a set of words the line contains. If you sort your own notes by keyword, you are sorting by the part of each headcanon that was never the point.

One roll already answers the question

This is the part that makes the definition usable. With all five families switched on, the bank draws one line per family, in a fixed rotation, until it has given you as many lines as you asked for. That is not a metaphor; it is what the drawing code does, and it means the number you pick is the number of families you get.

I replayed it offline: at counts one through five, 500 rolls each, the result had exactly that many distinct families every single time — 500 out of 500 at each count. At count five I ran 2000 rolls and found zero batches that repeated a family and zero batches that repeated a line. So a single press of Generate is not five random lines. It is a five-part answer to one question: one line from each family, covering what the character is like, where a habit came from, who they owe, what they do without noticing, and what they hold back.

Here is one such roll, reproduced exactly. In the name box: Tova. No tone switched on. All five families on. Count set to 5. First press of Generate. Above the five lines the tool prints Archetype: The Patient Storm — that label is drawn from a fixed list of 24 before the lines are drawn, and it is not a setting you can choose.

• [Personality / Romantic] Tova falls slowly, then all at once, and everyone around them notices months before they do.
• [Backstory / Funny] Tova was banned from a family board game at twelve, and the ban was never formally lifted.
• [Relationships / Funny] Tova is the reason the group chat needed a second group chat.
• [Quirks / Chaotic] Tova carries a bag that contains everything except the one thing needed.
• [Secrets / Funny] Tova reads the instructions, throws them away, and then does it their own way out of pride.

Three of the five landed in the same tone, because leaving tone open lets the rotation fall where it falls. That is the difference between a first pass and a styled pass: a first pass tells you the five things you know about a person, and a styled pass tells you the same five things in one voice. Do the first pass before you touch tone chips. If you want a specific tone, switching a tone chip on resets the counter and re-draws immediately, so the five lines you see after switching are the tone's own five.

Five lines is a complete first pass, but it is not the whole character. If you want to know which families to spend more than one line on, that is a separate decision with its own page: the five-family by six-tone matrix walks the 30 combinations and says what each one is for. And if you want the first pass written out on paper instead of on screen, the one-page template is built to hold exactly that.

What this bank never does

The definition gets sharper from the negative side. Here is what 180 lines of checked material never do, counted one line at a time:

• It never writes dialogue. Zero of the 180 lines contain a quotation mark, and none contains a question mark or an exclamation mark. There is no line anywhere in the bank that puts words in a character's mouth — which is why a line taken from here can never be mistaken for a line of the actual text.
• It never refers to the world outside the character. Zero lines contain a year. Zero contain money. Exactly one line in the whole bank contains a digit at all — one character makes decisions at 2 a.m. Nothing in the bank can be looked up, checked against a source, or contradicted, because nothing in it points at anything outside the person it describes.
• It never names a second person. Zero of the 180 lines contain another capitalised name, and the character's own name appears exactly once in every line, always at the start. Every line therefore survives a name swap unchanged.

Read those three together and you have the honest statement of what a bank like this can do. It hands you sentences in the correct shape — one claim, one person, nothing checkable, nothing spoken — with the character deliberately left out, because a bank cannot know your character. The shape is what it is good for. Gate three is where you put the character back in, and it is the only part of the definition a tool cannot do for you. If you want to see what a batch of raw lines looks like once each one has been annotated with what it is doing, the annotated examples are exactly that.

Where the boundary sits

Four words get used as if they were the same thing. The three gates separate them cleanly, so it is worth naming each of them against the test:

• Canon — the source settles it. Fails gate one, and that is a compliment: it means you can look it up instead of inventing it.
• Headcanon — the source leaves it open, it contradicts nothing, and it changes one behaviour. Passes all three gates.
• Fanon — a headcanon that enough people adopted that it circulates as if it were settled. The sentence itself did not change; only the number of people carrying it did. It still fails gate one, because the source still does not say it.
• AU or fic — it overwrites something the source settles. That is gate two, and it is a different document, not a better headcanon.
• Theory — aimed at the source rather than at your scene. A theory wants to be true; it hunts the source's own gaps and hopes to be confirmed. A headcanon only has to be usable, so it is allowed to be unprovable forever.
• Original character — no source character at all. With nothing to be open about, no gate applies, which is why an OC is not a kind of headcanon.

The one-line version, if you remember nothing else: a sentence is a headcanon exactly when the source could neither confirm nor deny it. If the source could one day confirm it, it is a theory. If the source has already answered it, it is canon. If it can never be answered by anyone, and it changes what the character does, it is yours. For the spelling and origin of the word itself — whether it is one word or two, and where it came from — this page covers that separately.

Five minutes, start to finished

The whole procedure, in the order that avoids wasted rolls:

• 1. Leave tone alone and all five families on. Set count to 5. This gives you one line per family, which is the complete first pass.
• 2. Read the five lines as five questions, not five facts: what are they like, where did a habit come from, who do they owe, what do they do without noticing, what do they hold back.
• 3. Run the three gates over each line in order. Reject on gate one and gate two without hesitation; spend your time on gate three, because that is where the real failures hide.
• 4. For every survivor, write one behaviour you could stage tonight. A kept line with no behaviour attached is an unfinished line.
• 5. Only now switch on a tone and press Generate again for a styled pass in the voice you want.
• 6. If two characters are sharing a page of notes, expect the pair to overlap — the bank is fixed at 180 lines, so the same line can be handed to two different characters, and the page on repeating lines is about what to do when it happens.

Quick answers

Is a headcanon canon? No, and it is not supposed to be. Canon is what the source settles; a headcanon is what the source leaves open. If your sentence gets confirmed later, it stops being a headcanon at that moment and becomes canon. That is a promotion, not a correction.

Can a headcanon be wrong? It can be unusable, and it can be out of bounds. It is out of bounds only when it trips gate two, by contradicting something the source settled — and at that point what you have is an AU. Otherwise it cannot be wrong, because nothing is available to make it wrong.

Do I need a generator? No. The three gates work on a sentence you invented in the shower. What a bank adds is different shapes: five families in one press instead of five variations on the idea you already had. If you do use one, remember it is drawing from a fixed pool, so the same five lines will come back to you eventually.

How many does one character need? Start with five — one per family — because that is the smallest set that answers all five questions. Most people then spend extra lines on Quirks and Secrets, since those two are the ones that show up as behaviour in a scene.

Is it one word? Yes, in the form the bank uses: headcanon. For the two-word and misspelled versions, and why they are not interchangeable, see the spelling page.

Why bother defining it at all? Because the definition is the filter. The difference between a page of notes that helps you write and a page of notes that does not is not how many lines are on it; it is how many of them survive gate three. Five lines that pass beat thirty that do not, and the test is the only way to tell them apart before you have written the scene.