He sees her everywhere.
Walking through the streets of New Rome, golden rays of sunlight peaking through the overcast that emulate her curls, he sees her.
It's hard to forget when the clouds share the same color of her eyes, or the droning of the Athena cabin reminds him of her voice resonating off his cabin walls.
She is (was) his, and no one could have taken that from him (but they did). He sees her everyday, almost haunted by the memory. And when he goes to bed every night, his dreams are filled with golden locks and grey eyes, smoky and all knowing.
He's a ghost of his former self. Of course life goes on, there's a war to win still, but what's the point? Friends and allies try to break him out of it, but it's no use.
He's haunted by the memories of Annabeth, falling into the bottomless pit—of Mother Earth's laugh as she claimed yet another demigod's life.
The end is coming, Percy can feel it—feel it down to the very core of his soul. He isn't sure of much, but he knows one thing.
He will have Gaea's soul—and the earth will tremble.