A son of Jupiter - the Roman aspect of Zeus - and praetor of Camp Jupiter. Wakes at the start of The Lost Hero with his memory erased. His arc through Heroes of Olympus is about the tension between Greek and Roman identity and what it means to lead. Thalia Grace's younger brother.

A son of Hephaestus with the rare ability to generate and control fire. The comic relief of the Heroes of Olympus ensemble who turns out to be carrying more grief than he lets anyone see. His subplot in Blood of Olympus and Dark Prophecy is one of the most satisfying payoffs in the series.

A daughter of Aphrodite with the power of charmspeak - the ability to make people do what she says. Self-conscious about her heritage in a series where beauty and love magic are considered less impressive than combat powers. Her arc is about redefining what strength looks like.

Praetor of Camp Jupiter and one of the most capable leaders in the series. Daughter of Bellona, Roman goddess of war. Her arc in Blood of Olympus is one of the series' best subplots.