Who Can Write Queer Characters?

The short answer: Anyone! 
The longer, much more accurate answer: Anyone who will write their queer characters with the same level of respect and dignity and research that they would any other character.

Queer characters should exist in stories, the same way they exist in the real world. Even if you’re not part of the LGBTQIA+ community, any world you create needs to acknowledge that queerness is part of life, part of story, part of humanity. 
Plus, writing stories is about blending our own unique reality with creative license, with imagination and deep ponderance of the world around us, including the parts we don’t know everything about. Great writers have great empathy, the ability to imagine what it’s like to live in someone else’s shoes. And wouldn’t this world, and literature in general, be incredibly boring if authors only wrote characters like themselves? 
What’s important is how you write queer characters.

Here are some things you need first.

1. Remember that queer people are just regular human people. This might seem too obvious to say, but there are a lot of ignorant forces out there working to convince everyone that queer folks are bizarre creatures with foundationally different motivations and desires than non-queer people. That’s obviously not true. If you want to write queer characters, you should already know that, and this should just be a reminder. If you don’t already know that, take some time to work on your compassion and social awareness, away from writing, and come back when that’s a foundational part of you, because if that’s not foundational to you, you can’t write characters well anyway.
2. Next, remember that YOU are just a regular human person. You don’t know everything. If you’re not queer, you don’t really know what it’s like. If you have queer friends, you still only have a limited view of queer existence. Even if you’re queer, you don’t know about other queer people’s existence, especially if you’re also part of a privileged group. But guess what? The same goes for any part of human existence! If you haven’t lived it, you have to always be listening to those who have. As an author, that means listening when a queer reader tells you something is problematic. No matter what you’ve been through, or what you’ve learned, you could be wrong. If you’re not open to critique of your work, you’re not ready to write seriously in general.

Once you’ve got those things down, then you can move on to the writing part.

Here are some things to keep in mind as you think about your characters.

1. Your queer characters need to be nuanced, individual, and well-rounded both inside and outside of their sexuality and gender (just like any other character!).
   Queerness is not a personality, it’s just one characteristic in a whole long list of complex characteristics that interact and intersect in such varied ways that no two people are the same. Intersectionality is the way that social characterizations interact and affect each other and result in varying social advantages, disadvantages, and privilege. A queer woman of color has a different experience in society than a queer white woman, and a poor queer person has a different experience than a wealthy queer person. 
   Even just within the single characteristic of queerness, there are so many varying ways a person can identify, like lesbian, trans, intersex, etc. The way a person identifies in their sexuality and gender is a web of many spectrums, from the label of sexuality they fit into (lesbian, gay, bisexual, asexual, etc.) to their gender identity. And there are still kinds of queerness that haven’t been labeled yet! Plus, every person feels differently about their own identity and their expression of it, thanks to their upbringing (were they taught that heterosexuality was the only acceptable sexuality?), the society they live in (a conservative small town vs. a more progressive urban area), their understanding of their own sexuality and gender (are they still figuring it out?), their past trauma or other experiences they’ve had (were they bullied for their differences?), and so much more. While all kinds of queer people are still fighting for full societal acceptance and even basic human rights, the less-understood or more-recently-labeled forms of queerness may face more struggles and dangers than other queer folks.
2. Avoid tropes and stereotypes. This is true of all of your characters, but it’s especially important when you’re writing about someone from a community to which you don’t belong. If you’re unsure if something is a stereotype, try asking yourself if your queer character matches a ’90s/early-2000s rom-com queer character. That was an especially trope-filled time in cinema for all non-cis-straight-white-male demographics, really. 
   Now does this mean you can’t use a single trait for your character that’s from a stereotype? No. Does that mean your male gay character can’t watch The Golden Girls or enjoy a Sunday brunch? Heck no. (I mean, who doesn’t?) But their whole personality, all their likes and dislikes, their mannerisms and body language, can’t be comprised completely of these kinds of characteristics that point always toward the stereotype. It’s boring, it’s lazy, it’s insulting, and it’s inaccurate. Similarly, if your book is full of a diverse group of characters and the most prominent characteristic of each is stereotypical, that’s not good.
3. Your readers will know if you only added queerness to your story for diversity points. Avoid quick flashes of queerness or short-lived queer characters, those who just pop into the story, mention they’re queer, and leave, especially in a way that doesn’t alter the story much. Also avoid adding queer characters whose whole purpose seems to be as a magical, wise, eccentric side character who helps give the hetero, cis MC the answers without doing the work.
4. Don’t shove these details in your story if and where they don’t make sense organically. If sexuality doesn’t matter to your story, then why would a queer character’s sexuality matter? When you're introducing a character in a scene where a group of characters are playing basketball, why would you need to bring up their sexual preference? It doesn't make sense, and your reader will see your effort to force that detail where it doesn't belong. If you're introducing a character by listing a lot of varied details about them, then it makes more sense to include their queerness. If you're writing a scene in which sexual preference is important, like your character is with their partner or going to a bar to find a date, that also makes sense. But when walking into a room? Do you know anyone who would do that?
   
   

Whether you're queer or not, writing any character takes empathy, a willingness to learn more, and an openness to critique. Read about and listen to those around you who live the experience you'd like to write, and remember to ask for help when you need it! I promise you that all the most successful authors have done just that.