The Empyrean series has seen a meteoric rise in popularity, with the latest installment, Onyx Storm, released earlier this year propelling all three books to the top of Amazon's Kindle best sellers list for 2025. The series' surge in readership began with the debut of Fourth Wing in 2023, which gained significant traction on Booktok. Since then, Rebecca Yarros' romantasy series has captivated a wide audience, consistently dominating bestseller charts.
The Physical Editions Are Popular Too
#### Onyx Storm (Deluxe Limited Edition)
1See it at AmazonSee it at Barnes and NobleSee it at TargetWhile the Empyrean series has been a powerhouse on the Kindle charts, its success extends to physical sales as well. Both the deluxe and standard editions of Onyx Storm are firmly entrenched in Amazon's top 10 best-selling physical books for 2025, with Fourth Wing also holding strong in the top 25. The only recent challenge to Onyx Storm's dominance came with the release of Suzanne Collins' new Hunger Games book, which briefly pushed it to the second spot on the fiction list. However, with more readers discovering the series through Fourth Wing, Onyx Storm could reclaim the top position before the year ends.
AnswerSee Results#### Fourth Wing and Iron Flame are Part of Kindle Unlimited#### Kindle Unlimited
35See subscription options.See it at AmazonFor those eager to dive into the Empyrean series, Fourth Wing and Iron Flame are currently available for free on the Kindle app through a Kindle Unlimited subscription. This provides an excellent opportunity for new readers to start the series without additional cost, as long as the books remain part of the subscription service.