The initial kernel of an idea came to me when I was at a local copy shop getting something printed. The manager of the place was this amazing goth guy. I’m talking stiletto nails, black lipstick, perfect eyeliner, and big dark hair, in a little work polo. He was magnificent—and a super good manager! I got my order filled expertly and left the place making up a story to my friend about how he obviously did black magic out of the back of the shop. 

K. Valentin – 20 October 2025

The Back Flap

Mateo’s mother forbade him from ever using magic, but now that she’s gone, magic’s his only marketable skill, and he’d really like an exorcism—which costs money he doesn’t have. What’s the harm in making a quick buck by calling himself an Occult Specialist and chanting a few half-remembered spells in his crappy Spanish?

Enter Topher, a naive nepo baby with a curse that keeps killing people around him. Most importantly, he’s rich and too clueless to clock that Mateo—and his (absolutely-not-the-assistant) astral-projecting best friend Ophelia—have never actually had a client before. Lifting Topher’s bad luck curse should be simple, but as luck would have it, nothing is simple, and Topher–who Mateo sort of, kind of likes–might be at the center of a deadly magical conspiracy.

To make matters worse, the more magic Mateo does, the stronger the demon inside him grows and the more he wants to eat people. But would caving to the urges of an ancient evil really be that bad if it helps him get a payday?

About the book

What is the book about?

An Amateur Witch’s Guide to Murder is about Mateo Borrero, a broke goth wannabe brujo with a demon trapped inside him. When Topher walks in, cursed, extremely rich, (kind of cute in a scared rabbit sort of way), and hoping for help, Mateo decides he can earn cash for an exorcism with a side hustle lifting hexes. Never mind that he doesn’t actually know what he’s doing…or that using magic accelerates his possession.

When did you start writing the book?

I started in March of 2021. It was originally a short story but my wonderful critique partners helpfully let me know I’d written a chapter one to a novel (this had happened to every short story I’ve ever tried to write).

How long did it take you to write it?

About a year to get to a roughly book-shaped thing. Another 4-5 months whipping it into shape with my agent.

Where did you get the idea from?

The initial kernel of an idea came to me when I was at a local copy shop getting something printed. The manager of the place was this amazing goth guy. I’m talking stiletto nails, black lipstick, perfect eyeliner, and big dark hair, in a little work polo. He was magnificent—and a super good manager! I got my order filled expertly and left the place making up a story to my friend about how he obviously did black magic out of the back of the shop. Additionally, I really wanted to tell a story about how weird it is being a Puerto Rican raised outside of Puerto Rico, away from my extended family, without cultural touchpoints and surrounded by people who barely know what Puerto Rico is (or that it’s part of the US). But, like, fun and couched in magic (and cannibalism!?).

Were there any parts of the book where you struggled?

Pacing, pacing, pacing! My natural cadence for what’s happening in a novel seems to be: amazingly slow up to the midpoint, and then every single thing in the world happens all at once. Course correcting from my slow start was a real struggle and still one of the hardest things for me to calibrate correctly. The harsh reality is, people want stuff to happen before the one-hundred-and-fifty-page mark (rude).

What came easily?

Mateo himself. There’s a certain flavor of bad retail job that leaves you soul-sucked, despondent, and listless. I easily channeled that into him because I too was once an extremely broke retail worker. Also, any dialogue. I love dialogue so much. If only characters could just float in space talking.

Are your characters entirely fictitious or have you borrowed from real world people you know?

I know nothing but fantastic weirdos so definitely tiny bits of certain people make it into my characters, though no one’s wholesale taken. A good example: one of my very best friends in the entire world, who I met as a teen, is the basis for every chaotic woman I write. She was (still is) the most delightful hellion, so I worked a little of her energy into the astral projecting best friend, Ophelia. Sometimes I take small things: Mateo’s height (6’3”) was inspired by another ride-or-die friend who’s even taller (6’7”). I stole his tall lanky vibes.

We all know how important it is for writers to read. Are there any particular authors that have influenced how you write and, if so, how have they influenced you?

I could go on forever but I’ll try to keep it short(ish). Martha Wells is top of the list. All Systems Red (Murderbot) blew my mind clear out of my skull when I first read it. The voicey-ness was out of control in a way I hadn’t experienced before. Reading those novellas gave me the courage to lean into my own voice and let the dark humor out. Similarly, Tamsyn Muir was out there writing hilarious and wildly profound books, opening a lot of doors for fantasy but make it funny (and kind of messed up). And I’ve got to take it all the way back to Stephen King. As a kid, I devoured his work. Somehow Misery of all books made me really want to be a writer.

Do you have a target reader?

Tired millennials probably connect the most, but also queer people who’ve ever been too dim to understand their own feelings (bi and demi represent!), fans of paranormal detective shows like Supernatural and Buffy, and people who like their humor horror-adjacent.

About Writing

Do you have a writing process? If so can you please describe it?

I love to trash draft—meaning my very first draft is super-fast and super-bad. It’s an exploratory exercise for me to get a hang of the characters, the tone, and the potential for plot. It’s totally pantsed and I give up on it whenever I feel like I know enough—this can be straight through to the end of a book-length thing or just a few chapters in. I just need enough to get the brain churning on a real story. From there, I have to fundamentally change everything and start over, properly plotting out the book all the way through to the end. I run through eight or so drafts, slowly forcing the novel into shape—with help from some critique partners and my agent along the way.

Do you outline? If so, do you do so extensively or just chapter headings and a couple of sentences?

I do. After the trash draft of the last question, before I do the real first draft, I like to use physical index cards. I start from the beginning and every scene gets one or two sentences of what’s happening on the card. I use these as my framework and from there I type up a more fleshed out summary-style breakdown of every chapter where I highlight the purpose of each scene. It ends up being the skeleton of my draft.

Do you edit as you go or wait until you’ve finished?

I do a lot of drafts, so I never get fussed with editing as I go. I’ve always got the next draft to fix things in. Sometimes I just make something red if I know it’s really jacked or totally wrong so I won’t lose it on revisions.

Do you listen to music while you write? If yes, what gets the fingers tapping?

I wish! Unfortunately, I need silence. I’m super jealous of anyone who can combine the two. I can barely handle writing in a café. If you ever see me in one, I’ve got headphones on blaring the sound of rain. I do listen to music to do writing-thinking, though. Big fan of Rezz, 2hollis, GG Magree, and Charli xcx (depending on the thinking-vibes needed).

About Publishing

Did you submit your work to Agents?

This was the third book I queried. I only sent out a few queries on the first book because some very correct (and kind) feedback let me know quick it had some fundamental flaws. Second book racked up about fifty rejections. I got my agent with my third book from a live pitch event. I was just trying to practice talking about my book—had no expectation I’d actually get rep from it—so I was elated to get her interest because she was my longshot dream agent.

What made you decide to go Indie, whether self-publishing or with an indie publisher? Was it a particular event or a gradual process?

I’d been on sub a few months, and my (now) editor called up my agent to talk about books she’d be interested in, and my agent ended up pitching my book. My editor read my book in, I think, three days. Super fast! And immediately made an offer. It was really exciting after a summer of slow sub responses. She really got the book in just the way you want your soon-to-be editor to. My agent also had some experience with this indie publisher from another author who I got to talk to, so I got a good sense of how supportive and savvy they would be before accepting which was great. I’ve felt really supported by their team, and they match my extra energy with all the silly little things I want to do. It’s been a wonderful experience!

Did you get your book cover professionally done or did you do it yourself?

My publisher found a wonderful artist, Ana Hard, to do the cover. I’ve been an art director for the last two decades so this poor artist did have to deal with what had to be the most opinionated author she’s ever met (sorry Ana). But the cover ended up super cute!

Do you have a marketing plan for the book or are you just winging it?

My publisher has a wonderful internal marketing team that made an awesome marketing plan in coordination with an external publicist I hired. They have me doing stuff like writing pitches for articles and book lists and they even ran a couple Goodreads giveaways (which was very cool). Additionally, I’ve got loads of super extra ideas for stuff. The internal team actually just helped me run a demon hand giveaway—love that they’re bringing my same ridiculous energy. On top of all of that, I’m also posting a lot on socials. Since this is a debut, I want to give it my all!

Any advice that you would like to give to other newbies considering becoming Indie authors?

Don’t give up! There’s an audience out there for your book, whether it’s an agent you’re trying to get, an editor you’re hoping will offer, or finding readers. It might not be your first, second, or third book, but if you keep trying, keep improving, and keep writing the kinds of things you wish you could read, you’ll find your fans.

About You

Where did you grow up?

I was born in England but raised in Las Vegas, Nevada—which means I legit went on field trips to casinos (casinos have amazing art museums and animal shows).

Where do you live now?

I live in Washington state, near Seattle. I fled here after spending my formative years in the center of the sun (Las Vegas).

What would you like readers to know about you?

I want to make you cry but I also want you to leave my work feeling good. Sailor Moon, Pinhead, Murderbot, and Victor Vale are my favorite characters (I contain multitudes). I hope if you check out my work, you enjoy it.

What are you working on now?

I’m in the early drafts of a new adult fantasy I’m super excited about. I can give you the one sentence: An accidentally treasonous devil prince and a revenge-fueled lesbian mage are forced to raise a devil baby together in order to make everyone who ever wronged them pay.

End of Interview:

For more from K. Valentin visit their website and follow them on Instagram and Bluesky.

Get your copy of An Amateur Witch’s Guide to Murder from Amazon US or Amazon UK.