From Rebecca Yarros' wiki:

Fourth Wing is a new adult fantasy romance novel written by the American author Rebecca Yarros. It is the first book in the Empyrean series,[1] following the journey of Violet Sorrengail, who is forced by her mother, General Sorrengail, to join the Basgiath War College and become a dragon rider in the kingdom of Navarre. Even though she has been trained her entire life to enter the Scribe Quadrant, Violet must endure deadly quests and competitions that push her to her limits while trying to avoid being killed by one of the most powerful riders in the quadrant, Xaden Riorson.

The book was published in the United States on May 2, 2023, by Red Tower Book, an imprint of Entangled Publishing. Its viral success within TikTok's reader community, BookTok, significantly contributed to its No. 1 ranking on The New York Times bestseller list. It won The International Book of the Year 2024 at the annual TikTok Book Awards. The book sold over 2.7 million copies in its first week and has been translated into approximately 30 languages.[2]

Yarros has mentioned in interviews that the idea for Fourth Wing emerged when her publisher announced that they were going to start a romantic fantasy line, prompting her to submit five proposals. After several reviews, her publisher selected the third idea, which explored the Empyrean world.[3] The inspiration for the story stems from her fascination with dragons, her military experience with her husband, and her personal struggles.[3] Violet's physical fragility, as described in the book, was influenced by Yarros's own experience living with Ehlers-Danlos syndrome, a genetic disorder affecting both her and her children. Yarros has expressed a desire to represent people with chronic illnesses, showcasing that they can also be heroic.[4]