So in Percy's great prophecy it's said to be fulfilled when he turns sixteen. But did he really turn sixteen on August eighteenth? In the Lightning Thief, when they are at the Lotus Casino, they don't age. It only seemed like an hour to them but five days passed outside. So Percy would have been biologically sixteen on August twenty-third, not the eighteenth. But wait! There's more Percy goes to Ogygia as well. And Calypso says that time doesn't really work on the island. And later she states that as long as he was on the island he would be immortal. So he didn't age then either. When he gets back to camp it's been two weeks since the eruption of Mt. St. Helens, so you have to add in fourteen days. So now his biological birthday is September eleventh. The prophecy obviously mean that the half-blood who would fulfil the prophecy would be biologically sixteen. Not chronologically, as Nico and Bianca were well over eighty chronologically. Did the prophecy not come true? Is it not set for another couple of years? Who was it talking about?