Sarah Rees Brennan has opened up about how she drew on Irish myths and legends when working on her Chilling Adventure of Sabrina novels.

The Irish author recently spoke to Her about how she got involved with writing the tie-in books for the Netflix show - and the big change she was able to make taking it from the screen to the page. "I was a big fan of Sabrina The Teenage Witch when I was growing up - especially Salem. And I really love Riverdale, I just love how it is so operatic in a modern gothic way. "It's like, let's play with nostalgia but also play with these operatic conventions and be like 'Oh, this guy got attacked by a bear - and now he's going to solve a murder!'  "When I heard that the Riverdale creator Roberto - who is a genius - was making Sabrina, I thought that was so exciting and I couldn't wait to watch it. And then I got [a query] asking if I'd be interested in writing tie-in novels for a TV show - and I was like, 'yeah, but for which TV show?' "They couldn't tell me outright. I was talking to a friend who was in the know and I was asking her what show it was, and she said 'it's the show you've been talking about for like six months - you're going to want to do this.'" She recalled how it was then that she figured out the offer was for The Chilling Adventures of Sabrina - and that it wasn't long until she signed on the dotted line. "It's a dream project that came to me by, it felt like by magic, honestly," she added. "I've always loved stories about witches. They are figures of such anarchy and going against the system, which is why they used to be seen only as villains. And now we've come to see them more and more as, I understand why a woman would want to work outside the system with dark magic or in any other way." So far, there are two Chilling Adventures of Sabrina tie-in novels. Season of the Witch, a prequel novel, is set during the summer before Sabrina's 16th birthday - as she knows that her world is about to undergo a massive change, and she tries to come to terms with leaving her friends (and Harvey) behind. Daughter of Chaos, which was released in December, takes place between Part 1 and Part 2 of the Netflix series - after Sabrina Spellman has just made the hardest decision of her life: leaving behind her beloved friends at Baxter High. Now it's time to follow the path of night and find her way among the witches and warlocks at the Academy of Unseen Arts. The third book in the series, Path of Night, is set to be released later this year - and will pick up in the aftermath of that Part 2 cliffhanger. And in the aftermath of Part 3's release last month, Sarah told us about the biggest change she was able to make from the series - and it's one we're totally thrilled about. "It's interesting to write the books, because in books you don't have a budget. You're like, 'special effects budget is in my head and it's unlimited!' Occasionally, Roberto or Ross, one of the writers on the show, will tell me a thing they wanted to do - and I'm like, I can do that, it's free [to do in the book]," she explained. "I can make Salem talk a lot more, so I've given him the personality from Sabrina The Teenage Witch - and that's been fun to do. "The [CAOS team] have been really great, they've been really lovely and collaborative. We've been on the same wavelength, and we've got a good idea of where the story's going - but that's not to say they haven't surprised me. I love that they're willing to take big risks with the story, because it means I'm able to take big risks with the books as well." Besides the Netflix series, the New York Times bestselling author told us how she drew on Irish myths and legends when developing the novels. "[I got inspiration] from lots of places. It's really fun for me, because I've read the graphic novels when I got the gig so that made me think about different ideas that they had there," she explained. "And we live in Ireland, the land of saints and scholars - so I borrowed from myths and legends as well, and horror movie tropes. "Because Sabrina uses a lot of horror, I looked at what myths tap into horror and what myths are genuinely stories you would tell after dark." Over the seasons, Chilling Adventures of Sabrina fans have become divided over who they want to see her end up with in the end: Nick or Harvey. So, where does Sarah stand in the debate? "Both sets of shippers - Harvey and Sabrina, and Nick and Sabrina - have claimed me as their own," she told us with a laugh. "They read the books and they're like, 'OK, here's what she definitely thinks.' "And now of course there's Prince Caliban. It's an interesting thing because people love a Prince, it's a power marker and it just seems exciting. I like Caliban, but I'm also like...I think we all know about that guy who tries to take ladies' jobs, I'm just like, 'stay away from her! get a job - another job!' "I like Caliban but I don't have as much of an emotional connection as I do with Nick and Harvey, who I both really love - so I can't choose between them. Sabrina can have either, both, whatever she wants."

• Season of the Witch and Daughter of Chaos, published by Scholastic, are both available now.