Complex sentence: The 10 year old demigod son of Hades and older sister Bianca di Angelo are rescued from a manticore by Percy, Annabeth, Thalia, and Grover.
Split into simpler sentences: The 10 year old demigod son of Hades and older sister of Bianca di Angelo. He and his sister are rescued from a manticore by Percy, Annabeth, Thalia, and Grover.