Christopher Paolini was 19 years old when he wrote his second book, Eldest. Paolini had started writing the Inheritance Cycle series while he was still a teenager, showing remarkable talent and creativity at a young age.
By the time Eldest was published in 2005, Paolini had already gained significant recognition for his debut novel, Eragon, which was published when he was just 15. This rapid progression in his writing career reflects not only his dedication to storytelling but also the impact of his first book, which set the stage for the continuation of the saga with Eldest.