The mad scientist. The batty neighbor. The homicidal maniac. From wild-eyed, mumbling homeless people to despondent teens dressed all in black and villains deranged by ambition.

There’s a long tradition of writing mental illness in fiction. Unfortunately, a lot of the time it’s been done poorly, relying on types and broad strokes rather than nuance and accuracy.

The stereotype.

The plot device.

The easy stock character.

When you write about mental illness, you are working in relationship to that hit-or-miss tradition, and you have to decide how you’re going to write.

What I would argue is that you really only need one principle: characters with mental illness are, in fact, characters. (Just as people with mental illness are, in fact, people.) Which means that they need to be written with the same care that all good characters are.

And what kinds of things do we care about when we’re trying to write good characters? Well, above all, we want them to be three-dimensional, because characters are supposed to be like real people, and real people are complicated and multidimensional. We don’t want our firefighter character, in other words, to only care about fighting fires; we don’t want a character from Kansas to care only about being from Kansas; and we shouldn’t want to write a character with mental illness in such a way that they are entirely reducible to that illness—a depressed person whose only attribute is sadness, say, or a person with a phobia who spends every scene being afraid.

But it’s bigger than the issue of dimensionality. When we write characters, we’re generally trying to make points of connection—people to whom our readers can relate in some way. That’s really why we make them dimensional. Even villains—the best villains often have some traits that we can understand, which makes them all the more fascinating. Points of connection are essential to fiction. But many times when people write characters with mental illness the result is a portrait not of commonality but of someone where oddness, difference, and otherness predominate. These portraits can get pretty offensive; they also make lousy characters.

I also think that this is the crux of why things go wrong when people try to get mental illness onto the page. Because it’s not just about the reader connecting; it’s about the writer connecting, too.

When you’re writing your way into a life that isn’t exactly the same as yours—whether the differences are slight or large—you’re faced with a decision: whether to empathize or not. Usually we embrace this opportunity, because there’s enormous pleasure in empathizing with people (even fictional ones). And you learn remarkable things, like how much you have in common with a wide range of human beings. It probably even makes you a better person, saying yes to that opportunity over and over again.

But what if the opportunity is threatening? What if you don’t want to find commonalities? What if you don’t want to blur (or even erase) the line between well and unwell, between you and a person with mental illness?

The fact is that there are commonalities whether you allow yourself to see them or not.

In my novel Miss Portland, the main character has bipolar disorder. (The book never comes out and says that, but it becomes clear soon enough.) Now, although I have wrestled a bit with depression, I do not have bipolar disorder. I’ve never experienced the kind of manic episode that my protagonist, Zoe, is experiencing throughout the book. But I chose Zoe as my protagonist because I have been very close to some people who have had bipolar disorder—close enough for their lives to inform and surround and shape my own. I wrote the book because I wanted to get closer still. And that meant treating Zoe like a character, which meant treating her like a person. A person with bipolar disorder, yes, but also a person with a great sense of humor and a very jumpy stomach and a nice brother and a person who is Jewish and from Philadelphia and who’s done a lot of different kinds of jobs in her life, including being a mindfulness coach. In other words: a person.

And of course the thing happened to me that always happens when I say yes to a character: I found myself in her and I found her in me. I found that the lines are in fact quite blurry, to the extent that there are any lines at all.

Characters—with or without mental illness—are not conveniences, not types to be slotted into places where the plot needs them. They are doorways into lives, into whole universes.

Some of those doorways might be frightening to you.

Open them anyway—all the way.