Young Adult Literature; Fantasy; Fairy Tale
Azalea struggles with a lot of normal teenager stuff: her relationship with her parents and siblings, developing her first crush on someone, and figuring out how to navigate the obstacles life throws at her… which include a homicidal undead king. You know—the usual. This combination of traits leads us to categorize Entwined as young adult literature (teenager working through stuff) and as fantasy (magical stuff), but there are also elements of fairy tale thrown in the mix.
For one thing, the plot is based on the fairy-tale plot of the Grimms' tale "The Worn-out Dancing Shoes." Plus there are free-floating fairy-tale plot points: princesses, magic oaths, an enchanted pavilion, an absent mother figure, a royal marriage to be negotiated, and so on. Keeper even references some of this stuff when he tells a captive Azalea:
"In a certain country […] There were twelve dancing princesses […] And their little hearts were broken. But one day, they found a magical land of silver and music, where they could dance and forget all their troubles." (25.58-60)
So while the plot of Entwined is too complex for us to consider it actually a fairy tale (it's a novel, after all, and most fairy tales are much shorter than that), there are sprinklings of fairy-tale elements, kinda like fairy dust, scattered throughout.