battle's aftermath, Nico avoids Will, convinced that the son of Apollo will now see him as a monster and want nothing to do with him, Nico having shown signs of a possible attraction to Will while working together on the battlefield. To Nico's surprise, Will forcefully tracks him down and orders Nico to spend three days in the infirmary recovering, berating Nico for avoiding him in the process. Nico comes out to Percy and admits his former crush on him before joining Will. In The Hidden Oracle, Nico and Will are shown to have started dating each other in the six months since the battle. When Will's now-mortal father Apollo arrives at camp, Will and Nico aid Apollo in his quest and in adjusting to being mortal. After the battle with Nero's forces, Will treats the worst of the camp's cases of hay fever caused by Apollo's plague arrow. In The Tower of Nero, Nico has become depressed following the death of Jason Grace on top of all of his other losses while Will is supportive and concerned for his boyfriend. During the final battle with Nero, Nico and Will help Apollo alongside the troglodytes, with Will at one point suddenly arriving with Camp Half-Blood reinforcements, as Nero apparently has the upper hand. Following Nero's death, Will coordinates treating everyone's injuries and helps Apollo prepare for his final battle with Python. Two weeks later, Apollo, now a god once again, visits his son and his boyfriend, and the two reveal that Nico believes that a voice that he's been hearing calling for help from Tartarus is Bob. Will plans to join Nico on his mission into Tartarus to try to find out what happened to Bob and to rescue him if he can, enlisting the help of the troglodytes to get in and out. Rachel provides them with a prophecy. Calypso Calypso is the daughter of the titan Atlas, who is imprisoned on the island of Ogygia for supporting her father during the first titan war. She first appears in The Battle of the Labyrinth, where she nurses Percy back to health. She falls in love with Percy and is heartbroken when he has to leave. Percy asks the gods to release her at the end of The Last Olympian, but she is still residing there when Leo becomes trapped on Ogygia in The House of Hades, having been released