 Nico's suggestion that Percy takes on the curse of Achilles and his work to convince Hades to fight in The Last Olympian is crucial to the Olympians' success and earn him a short bout of fame.He is privy to the fact that there were two camps, one Greek and one Roman, before The Lost Hero, making him an important liaison between the two groups in the latter series.He brings his half sister Hazel back from the dead and establishes her at Camp Jupiter.