The son of Jupiter/Zeus and a TV actress, Jason is a blonde-haired, blue-eyed teen with a scar on his lip. He also has a tattoo with lines and the letters SPQR. For most of the book, he has lost his memories, but he has the strong sense that people are always in awe of him because of his father’s identity. He feels the burden of being a demigod keenly, and is not sure he has the confidence needed to prevent the end of the world.

As Jason regains his memories, he realizes he is skilled in battle, and has the power of flight as well as the ability to control the air and call down thunder and rain. He has fought and defeated many monsters and Titans. However, he is also humble and appreciates his friends’ talents. He is always ready to sacrifice himself to protect others.

As the novel ends, Jason feels great affection for Leo and Piper, and is especially torn by his strong attraction to Piper. He has the sense that in his other life, as a Roman demigod, he had other friends, and even another girlfriend. He is hesitant to act on his feelings for Piper out of fear of confusing her more.