As always, let's first define what foil characters are, then we can better discuss why they're important, and, most importantly, how to implement them into your own writing.

What are foil characters? Foils are characters who are opposites of each other. The purpose of characters that oppose each other is to highlight the qualities of each. Of course, by this I do not mean that these characters are polar opposites. Rather, like yin and yang, they have similarities that work in harmony to highlight and compliment one another. The dark yin has a dot of bright yang, and bright yang has a dot of dark yin.

Foil characters should oppose and compliment one another; they balance one another out. To illustrate this, I want to mention some foils from Avatar: The Last Airbender and describe how they balance one another. Now, I know I refer to Avatar: The Last Airbender for examples quite often, but there are a couple of reasons for that:

The show is well-written

The characters are complex and 3-D (in character, not in animation ;) )

The show is targeted at a younger audience but shows a mature writing style that all ages can enjoy and relate to

It's a popular show, so many people don't have to sit and wonder what the heck I'm talking about

I freaking love the show and I want to talk about it. Sue me

So, first off, I want to talk about Zuko and Aang.

Now, before you go and say, "Yeah, this one makes sense. They're enemies for most of the show. Next!" let's take a step back and remember that foils does not necessarily mean rivals or enemies. Foils can be on opposing sides, sure, but that is not what constitutes a foil. I'll talk more about that with the next pair, but for now, let's start with Zuko.

Zuko is hot-headed, goal-oriented, and can hold a grudge indefinitely. He is short-tempered, to say the least. Zuko keeps everyone at a distance, even his uncle, who has loved and encouraged him from the beginning.

Aang, on the other hand, is patient, forgives easily, and is easily distracted. He has a very long fuse, but once that fuse is burnt out, it's out. Aang wants to be friends with everyone, and he loves with his whole heart.

These two are starkly different. Aang is loving and kind, Zuko is filled with anger and hostility; Aang makes friends with anyone and everyone, and Zuko keeps even those closest to him at arm's length.

Let's not forget about their symbolic physical characteristics that foil each other. For both Aang and Zuko, their physical symbolism is in their eyes and ears.

Zuko's left eye and ear have been badly wounded, and though it is never out-rightly stated in the show, it is more than likely that his sight and hearing are impaired. This symbolizes Zuko's inability to clearly see the right path, as well as his refusal to listen to his uncle's words of wisdom.

On the flip side, Aang's eyes are unusually large, as are his ears, something that's out-rightly commented on in season one episode fourteen, "The Fortuneteller." These traits symbolize that not only is Aang's vision clear, but he can see more than your average person, which leads to his distracted behavior. His large ears symbolize Aang's ability to listen to the council of others and take it to heart.

These two characters are very different, but they also have so much in common. Great burdens were placed upon both of them at a young age. Both of them have great expectations thrust upon them. Both of them had their people turn their backs on them, Zuko being exiled and dishonored, Aang being excluded from his friends' games and taken away from his teacher. Both are passionate. Both had a wise old man take them in as their own and teach them and love them as a son. Though they are so different, they are also very much alike-- season one episode 12, "The Storm" was basically entirely dedicated to highlighting this!

Next, I want to talk about foils on the same side, and to illustrate this, I've turned to Toph and Katara.

Toph is tough, stubborn, and, most importantly, independent. She hates feeling like other people view her as a helpless little girl who needs to be taken care of. She can take care of herself by herself, and she doesn't want anyone telling her what to do.

Katara's mother was killed by the Fire Nation when she was very young, and ever since, Katara has taken up the mantle of woman of the house and has adapted to a sisterly/motherly role. She is empathetic and shows her love through caring for others, and this is where her conflict with Toph is most evident. Toph doesn't want to be taken care of at all. Toph is independent, which means in her mind, everyone should pull their own weight-- no more, no less. But Katara shows she cares by taking care of the people she loves, and she has a strong sense of community, which means in her mind, everyone should help to haul the collective load.

Katara and Toph may be on the same side in the main conflict of the story, but there are many times when they are on opposing sides. For example, in season three, in the episode titled "The Runaway," the gang needs money, and Toph has the great idea to use her seismic sense and Earthbending to hustle various scammers to get more money. With each hustle, and scams get more intense, and the group quickly acquires more than sufficient funds. Katara begs the others to stop. Toph outright refuses, saying Katara is just trying to stop their fun and that she's too motheringly smothering.

At the end of the episode, Toph and Katara have come to a standstill, and they've learned to respect one another and how to show their care for each other according to the other's personality. This isn't the first time these two clash heads, but it's one of my favorites, as it really shows a clash of their personalities, making it a prime example of how Toph and Katara are foils. Toph not wanting to be babied clashes magnificently with Katara's instinctive motherly behavior. They oppose each other in their expectations of one another and how they show affection, but they complement one another in the way they both want to be friends and they always protect one another.

Now that we've thoroughly defined what foils are, let's discuss why they are important. Like I said before, the opposition of foil characters highlights the qualities of each. Just as Zuko's hot-headedness highlights Aang's easy-go-lucky attitude, or how Toph's rebellious independence brings closer attention to Katara's maternal behavior. Foils allow a writer to discreetly bring attention to characters without saying it out-right-- in short, it allows writers to show rather than tell, which is always the goal. Going from Zuko's "I DON'T NEED ANY CALMING TEA! I NEED TO CAPTURE THE AVATAR!" to Aang's "Will you go penguin sledding with me?" and Toph's "I'm pulling my own weight" to Katara's "Even Momo does his fair share" helps give special attention to these characteristics without Zuko saying, "I HAVE ANGER ISSUES!" and Aang cheering, "I wanna blow off my responsibilities and just have fun!" or Toph saying, "I'm a strong, independent earthbender who don't need no help from no one" and Katara gushing, "I've only known you guys for five minutes but if something were ever to happen to you I would kill everyone in the Fire Nation and then myself."

Great, so we know what foils are, we know why they're important, but now what? How do we write them?

First off, you should never write a character whose only function is to be a foil for another character. If a character is only there to oppose another character, that character is useless. That's like making your friend wear something hideous to make your outfit look better-- childish and awkward.

Of course, that's not to say that other characters should not come into consideration when creating a character. If you have a lot of really smart characters, adding an averagely- smart character to balance things out can be a good idea, but that cannot be that character's only purpose. Make that character a smart aleck, with a wit so sharp it leaves the smart characters feeling dumb. Or make their logic somehow logical and illogical at the same time so that it leaves the smart characters frustrated that it doesn't make sense, and yet they can't dispute it because it does make sense. In short, characteristics can be given to a character for a foil, but a character should not solely function as a foil.

How do you write foils interacting? When writing dialogue, everything any character says needs to not only push along the plot, but also reflect that character's personality and motivation. Everyone wants something. Let your characters' behavior show that on an individual scale. Then, make the character with foiling personalities clash. Got a character that is painfully shy and just wants to disappear back into her room? Let her stick to the walls and corners of the room and only speak when spoken to, and even then make her flustered and panicked. Got a character who treats life like a party everyone should be invited to? Make him constantly change the topic or complain about the serious tone of discussion and encourage the group to wrap things up quickly so they can get to more fun things. Make him practically pull the shy one into the center of the room and draw attention to her behavior and desire to leave. These characters foil one another. They both want to leave, but the shy girl wants to leave for solitude, and the party animal wants to leave to have fun. This is how you write foil interactions-- any interaction, really, but I digress (for now).

All in all, foils are an important part of writing, as they can highlight and compliment one another, creating a balance among your characters. However, a character's only function within the narrative should not be to provide that foil. Just as no two people are the same, no two people are completely opposite either, and your writing should reflect that.

Can you think of some other good foil characters from Avatar: The Last Airbender we didn't discuss? Let us know in the comments who and why you think they foil each other. Don't feel like doing that? Here's a fun topic of discussion: How is the relationship between Sokka and Katara a foil for the relationship between Zuko and Azula?