In order to enhance or clarify your protagonist, a foil must be different in a significant way. Ideally, all your characters will be fully formed and uniquely voiced, but the foil's purpose in a narrative is to provide contrast in a way that is key to your protagonist. This contrast may be big or small, a source of conflict, tension or love. It may be physical, mental, emotional, philosophical, financial, cultural, ideological, and any other -al you can think of. And here's the kicker: every character in your story who is not the protagonist is, to some extent, a foil character. That's a nice specific definition, isn't it?! So how the heck does this actually work?
Apparently, "foil" as a literary term came from a 2000 B.C jewelry treatment in which gems were mounted with a foil backing to enhance or clarify their sparkle. That makes sense – a foil character's purpose is to enhance elements of the protagonist or clarify their actions and choices – but I have always preferred to think about writing foil characters in terms of fencing. Where a foil backing on a mounted jewel is a static, immovable thing, fencing is active, surprising and based in opposition. A fencing foil is one of three swords used in competition. It is very flexible and light, weighing less than a pound. To score, the opponent must be hit by the foil's tip only on the bodice of the uniform. Think about that in terms of writing a foil character: don't be heavy handed, be flexible, aim with purpose and go for the heart.
Antagonist as the foil
I've read many craft books that emphatically state that the antagonist is not and cannot be a foil for the protagonist. Every time, I asked "why not?" and the craft book stared back at me blankly. To make a logic statement out of it, I believe that every antagonist is a foil, but not every foil is the antagonist. An antagonist is acting in direct opposition to the outcome your protagonist desires and strives for. In terms of a key contrast, they don't get much more key, or more contrasting, than that. But there is a limited scope for nuance with the antagonist as foil. Their key difference will likely be ideological – your protagonist thinks the world should be one way, and the antagonist thinks the opposite. It may also be something else, like a physical trait –the protagonist has dark hair and the antagonist has red hair – but to have properly heighten stakes in your central conflict, this must also be tied to an ideology or world-view: the protagonist believes that anyone can and should have hair of any color and the antagonist thinks all hair should be red.
While the antagonist is a foil that will reveal much about the main character, other characters can provide insight for those moments when the stakes aren't quite so high.
Secondary characters as the foil
For most writers, this is the bread and butter of the foil. If not every foil is an antagonist, every secondary character is a foil. Think sidekick, parent, sibling, boss, employee, partner (in love or crime or both), neighbor, Lyft driver, BFF, ex-lover, teacher, crush-from-afar, postal carrier, tailor, hair stylist – anyone the main character notices, interacts with, or remembers.
Remember that adage, which you may or may not subscribe to, "show don't tell?" This is where your secondary characters really sparkle, foil-wise. A fencer might have skills or techniques, but in competition it all comes down to the opponent: our hero fencer must be able to react in the moment to the opponent's foil. The same is true of your main character when they are in scene with others. When you write a scene between your main character and one or more secondary characters, the way your protagonist reacts in the moment shows the reader as much, or possibly more, than the protagonist can tell about themselves.
How about this: your main character thinks of themselves as a kind person. But when they are on shift at work with Gertha the Gossip, the reader is shown that they can be as mean as anyone. Or: your main character prides themselves on being open-minded to other people's point of view, until family Christmas dinner when they are sat next to their uncle who voted for the other guy last election. Or: your main character has described themselves as generous to others. They are on a date in a restaurant and their dining companion criticizes the way they treat the servers. Or the opposite: your main character's date reinforces the idea that the protagonist is generous to others by leaving what the main character thinks is too small a tip. Or: your main character thinks another person is absolutely awful but after a scene or two together, the protagonist realizes that they have a lot in common and maybe that makes them awful, too?
- How does your protagonist react to other characters?
- Does the reaction in the moment, in the scene, reinforce or upend the way we have thought of them up until now?
- And, crucially, how does that show the reader exactly how human your main character is?
Self as foil
One of my favorite kinds of narrative is when the reader understands the protagonist better than they understand themselves. Foils help with this – especially how a main character might make choices or exhibit behavior in reaction to a secondary character – but almost every human has their own internal dialogue that can be just as revealing. Remembering that foils offer clarity most often in the form of small tensions, how can a person have tension within themselves? That's a trick question, of course, everyone experiences self doubt, recalls memories incorrectly, mishears information, has a belief about themselves that is ultimately wrong, or in the most extreme characters, self-mythologizes.
- What is it like when your protagonist believes something about themselves that simply isn't objectively true?
- How does your character engage with the spectrum of denial to self-awareness?
- And what behaviors and choices does that manifest in them?
Situation as foil
As we have seen, a foil can be anything that prompts the main character to react in some way that reflects their choices and behaviors to the reader. Usually, the foil and source of small or large tension is a person. But not always.
How about this: your main character has described themselves as a pacifist and a pragmatic realist or has displayed behavior and choices that reflect this world-view. One afternoon, they are on their way home. They had to skip lunch and they are hungry. The whole way home they are dreaming of a cheese-and-pickle sandwich. It will be the most glorious cheese-and-pickle affair since sandwiches were invented. Ideally, the craving means something to the character – it's what their stepmom used to make them after a bad day, or it is their absolute favorite thing to eat, or they are pregnant and all other food makes them nauseous. When the main character gets home, they find that not only are there no pickles left, but someone put the jar of just-brine-no-pickles back in the fridge. Gasp! How does your pacifist, pragmatic, realist main character react? Do they fly into a murderous rage? Do they accuse someone else in house of eating the pickles on purpose? Do they remember with a laugh that they themselves finished the pickles late last night? A foil can be anything – person situation, pet, weather – that prompts a reaction from the protagonist.
Situation as foil is particularly useful in genres that don't always have an antagonist, like writing for young children and comedy. From picture books through to narratives for middle grade readers, the main character is often not at odds with an antagonist. Rather, they have a problem to solve by the end of the story. While fairy tales might be laden with "bad guys," modern stories for young readers rarely are. In these cases, the young protagonist, or their animal/monster/acorn stand-in must react and respond to a situation – a new baby sibling, a runaway dog, the first day of kindergarten, changing seasons, having a birthday party, etc.
The same is true in situational comedy. Unlike drama, sitcoms usually lack an antagonist. Instead, they center around a ground of people – family, friends, co-workers – who are foils of each other, and the situations they get themselves into. Without a wacky situation, the characters would otherwise be in a state of relative stability. The situation is the prompt for reactionary choices and behaviors.
One last example of situation as foil can be found in odd-couple narratives. Say the last flight is cancelled on the day before Thanksgiving and two strangers share a rented car journey across the country in order to make it home in time. Neither of these two characters are the antagonist of the story, since they have the same shared goal, but they are certainly each other's foil, and hilarity ensues. In literature we can see this play out in George and Martha or Frog and Toad – stories where the characters are not at odds with each other, but with the context, circumstance or situation.
As aluminum foil is reflective when perfectly flat, a foil character or situation can offer mirror-like clarity on your protagonist. But what if the foil is crumpled or bent? How clear is that reflection now? If a secondary character or antagonist doesn't have their own truth that needs reflecting – remember, everyone is the hero of their own story – then they will be tokens in your narrative, not fully realized, compelling characters. No human is a perfect reflection of another, just as no character can be. And therein, fellow writer, lies the fun.