Newcastle-born Eliza Clark, 30, went viral on TikTok with her 2020 debut novel, Boy Parts, a violent, darkly comic thriller with a fetish photographer for an antiheroine, published by indie press Influx. By 2023 she was a scrappy outsider no longer, having moved to Faber with a second novel (Penance, presented as a true-crime story of a murder among teenagers) and scored a place on Granta’s once-in-a-decade list of 20 best fiction writers under 40. Now comes her first short story collection, She’s Always Hungry, a firecracker of a book that blends horror with speculative fiction and fantasy as it delves into themes of gender and power. She lives in south-east London.

What appeals to you about the short story?
It’s a little self-contained thing. It’s nice to give yourself space to experiment with different stuff – to have a bunch of ideas that you can explore and a bunch of worlds that you can play with. This has been the most fun I’ve had with a project because so much of it was so old, it didn’t even feel as if I’d written it. I could dramatically change and improve it, which is really satisfying.

Where do you find your inspiration?
The title story [about a boy in a matriarchal fishing village who catches and keeps a mermaid-like “finwife”] was inspired by a chapter in Killing for Company, the Brian Masters book about Dennis Nilsen, where he talks about the culture of the fishing villages in Aberdeenshire that Nilsen grew up in, and I’d wanted to do something with the idea of having this mythical creature and keeping it. That comes in part from a couple of Japanese films, Marebito by Takashi Shimizu, and Hideshi Hino’s Guinea Pig: Mermaid in a Manhole. The creature is often quite submissive, and I was interested in changing that.

Tell me about the decision to include content warnings. Neither of your previous books carried them, right?
No, and I felt a bit – not bad about it, but when I get tagged in a review, people generally say: “You should really check content warnings on this one.” I think there’s a lot of value in them, but they can be quite spoiler-y which is why they’re at the back.

Parasitic infestations, cannibalism and “pustules and rot” are all listed. Do you have any rules when you’re writing the gory bits?
I recently saw The Substance. The last half-hour is really heavy on prosthetic effects, and I was like, wow, I wish every film ended like this. When I’m writing about that stuff I guess I’m thinking about films that I like, which is actually not a very good thing because it can lead to quite bad prose, but I try to have a light hand and keep descriptions short and effective.

How do you feel about the collection being marketed as horror?
I can already tell that there are going to be loads of people who pick this up expecting it to just be horror from start to finish. I would definitely like to work more in horror – I’m so influenced by it but feel I’d struggle not to pollute it with something else.

What are some of the positive and negative aspects of being a writer today?
It can be a lot easier to find a niche and an audience but I often struggle with the signing table. I’m not very good with eye contact and being on best behaviour. I sometimes feel really jealous of writers who were working before the “you’re shit and I hate you” era of social media, too.

Is it worse for young women?
Definitely. There’s also the classic thing of a young man publishing his debut novel and there’s this immediate attempt to shove it into a canon – it’s just like Kerouac or Bukowski. Whereas when you’re a young woman, you’re compared to this other woman that had this book published six months ago. Career-wise, I’m looking forward to being an older writer.

Are things getting any better?
I feel like we genuinely are publishing more young female writers, I just don’t think we’re respecting them. When they announced the Granta list, a male journalist wrote this incredibly effusive paragraph – paragraph – about Graeme Armstrong. I’m not saying Graeme Armstrong doesn’t deserve a whole paragraph, but Sophie Mackintosh got two sentences, and then below that, “more in this vein with Eliza Clark, Lauren Aimee Curtis and Camilla Grudova”. I’d never felt so profoundly disrespected in my career, particularly because that vein is so broad. It felt so flagrantly sexist and reductive.

Did you write as a child?
In school I would always write pages and pages and pages, and then be sent home with my own exercise book to write stories in. I never really did – it’s difficult to keep up a sustained writing practice when you’re eight – but at 13 or 14, I started writing fan fiction, and with an audience became super-prolific.

Do you have a writing routine?
I don’t sleep very well and the idea of me doing work before midday is very unlikely but I’m quite happy to sit and work until two o’clock in the morning. Sometimes when I see the way other people talk about writing I think, why do you do it? It doesn’t sound like you’re having fun. I wouldn’t write if it wasn’t my favourite thing to do.

What are you working on now?
I’ve been working on a third novel for nearly two years, kind of in a speculative space. There’s definitely a version that’s very commercial, that could do really well, and there’s definitely quite an off-putting version. It’s been interesting thinking, what do I want to do with this?

Who are your literary influences?
My first favourite author and one of my most influential is Stephen King. That was what I cut my teeth on.

What have you read lately that you’d recommend?
Negative Space by BR Yeager, an independently published horror novel. It was so, so good – like, here’s what you can do with a novel. Also, The Sluts by Dennis Cooper, which I couldn’t believe I hadn’t read before. It’s one of those books that feels like it should have been super-foundational. If you’re stuck with reading, I recommend The Time of the Hero by Mario Vargas Llosa. It’s published everywhere else as The City and the Dogs, which is a much better title.

What’s next on your reading pile?
I’ve been quite bad for bouncing around a bunch of authors and not focusing on one to get a better sense of their whole oeuvre, so I’m going to read more Dennis Cooper. I could do with reading more Ursula K Le Guin as well. I read The Left Hand of Darkness last year and found it revolutionary.

How do you arrange your books?
Our shelves are colour-coded, which I always feel deeply embarrassed about. When we moved into our flat my partner was like, “Shall we colour code our books?” And I said no. It does actually look really nice but it’s a nightmare to find anything.

• She’s Always Hungry is published by Faber (£9.99) on 7 November. To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply