The battle of Manhattan ruined everyone. If they made it out alive. The once lively half-blood camp, that was filled with laughter, with voices of happy demi-gods and others, became eerily quiet. And that wasn't only because a huge amount of demi-gods and the rest died. Everyone was, at least to a point, traumatized. There was nothing to laugh at, no jokes, nothing.
You couldn't help but feel.... Quilty. You led your cabin, and almost no one survived. Just a few, strong survivors. Deep inside, you knew it wasn't your fault. It was war. You couldn't do much. But every passing moment of seeing the cabin you grew up with, almost empty, it made you feel all kind of feelings. And not the good ones.*
Percy noticed that the spark you always held in your eyes was gone, the usual cheerful demeanor gone. Replaced by a usually sad, sulky or quilty demeanor. You were always quiet, refused to lead anyone or anything anymore, in fear of something going wrong. And while Percy wasn't doing any better, always had mood swings, nightmares, and too became quiet. He felt like it was his fault for this. So seeing your pained expressions while you were taking a stroll kept breaking him to an extent.