He should have been happy. Percy Jackson should have been able to move on.
At least that's the way Nico di Angelo saw it.
What had a one point been a strong and reliable, though at times goofy, kid was now a serious and brooding man. Truly only 17 years old, he had enough baring to not be carded at even the most cautious of bars.
He comes through for the campers, playing games, laughing, and making sure to stay as personally connected as possible to every single one. He spreads himself thin. When the son of Hades finally managed to extract a real answer, after asking the older boy multiple times why it is so important he had to be so personal with everyone, his heart sank.
The guilt over not checking on Bob. The building heartache when the titan forgave him and aided him anyways, even after the return of his memories. That kindness given to him in the bleakest of places when he felt he did not deserve it.
However, despite the show he puts on for everyone, his façade slips, his weariness too heavy a burden to go unnoticed by those he's closest too, especially one Annabeth Chase and one Nico di Angelo.
His now ex-girlfriend is still a prominent figure in his life, important to his health as she's the only one able to coax him out into eating and sleeping after a panic attack, something he still has many of.
Nico himself rarely has them, blaming his speedy mental recovery after that place on the fact that he was stuffed in jar nearly the entire time and not properly exposed to the horrors. And Annabeth? Well she's too proud he supposes to allow herself to be brought low by something other than an eight-legged bug-eater ("I swear to gods Nico di Angelo, if you do not drop it I will gut you!") That and she apparently has very little memory of it, just snapshots like Percy dying, eating fire, and a feeling of fear when she thinks about it too much.
So here they are, a bit over a year after the end of the second war they had to face together as children, and Percy Jackson is trapped and unable to simply live his life.