The Heroes of Olympus is Rick Riordan's sequel series to the Percy Jackson and the Olympians series. It focuses on Greco-Roman mythology instead of only Greek mythology. The novel details a conflict between Greek demigods, Roman demigods, and Gaea.
“This is Annabeth,” Jason said. “Uh, normally she doesn't judo-flip people.”
― Rick Riordan, The Mark of Athena
“Blackjack," Percy said, "this is Piper and Jason. They're friends."
The horse nickered.
"Uh, maybe later," Percy answered.
Piper had heard that Percy could speak to horses, being the son of the horse lord Poseidon, but she'd never seen it in action.
"What does Blackjack want?" she asked.
"Donuts," Percy said. "Always donuts.”
― Rick Riordan, The Mark of Athena
“I still don't understand what a sea god would be doing in Atlanta."
Leo snorted. "What's a wine god doing in Kansas? Gods are weird.”
― Rick Riordan, The Mark of Athena
“Being a hero doesn't mean you're invincible. It just means that you're brave enough to stand up and do what's needed.”
― Rick Riordan, The Mark of Athena