The Chalice of the Gods

Percy Jackson is the protagonist of The Chalice of the Gods and all other books in the Percy Jackson and the Olympians series. He appears in many other books by Rick Riordan as well. Percy is the son of Poseidon and Sally Jackson. Percy struggles in school; like all demigods, he has ADHD and dyslexia, which makes academic work challenging. Nevertheless, Percy works hard and dreams of attending New Rome University, a college for demigods in California. Percy looks forward to the future when he is an adult who can leave behind most of The Challenges of Being a Demigod. Monsters usually stop attacking demigods who reach adulthood. 

Percy is well suited to confront and overcome Geras, the god of old age, because he has already thought a great deal about his own mortality. He has already chosen not to become immortal, even though the thought of a mortal future can be daunting. In contrast to gods like Ganymede and Hebe, who are disgusted by the idea of growing old, Percy sees the future as a gift that he can share with his loved ones. Percy realizes that the only alternatives to growing old are dying young or becoming immortal and never changing.