Leo (one of the seven) thought he was the one who had to die because he was with Percy, Frank and Hazel when the goddess of victory told them one of them were going to die, he also had fire. He thought he was the only person in both categories, but he wasn't Percy was also in both categories. Percy was there when they were told that one of them would die, and he can create hurricanes, a type of storm. Percy could have killed Gaea over the lake. Just saying.