A son of Jupiter (the Roman manifestation of Zeus) and actress Beryl Grace, Jason has an older sister, Thalia, who is a lieutenant with the Hunters of Artemis and a daughter of Zeus. Jason's character was introduced earlier in The Heroes of Olympus series. When he was a toddler, his mother abandoned him at the Wolf House, where Lupa and the wolves raised and trained him, eventually bringing him to Camp Jupiter. There, he rebelled against the expectations placed on him as a son of Jupiter, though he eventually rose to the role of praetor. Despite being raised in the “Roman” way—to follow rules and do his duty—he didn’t feel that he fit in there.

At the beginning of The Heroes of Olympus series, Hera stole Jason’s memories, contriving to send him to Camp Half-Blood, where he met his love interest, Piper. In The Blood of Olympus, Jason comes to terms with feeling as Greek as he does Roman and chooses to embrace both sides. In this sense, Jason exemplifies the need for reconciliation. The reconciliation that must happen on a larger scale between the Greek and Roman demigods—as well as within each of the gods of the pantheon—also happens within Jason as an individual character.