More than anything else he's been able to tell himself, it's the way that Annabeth agrees with him that has him finally relaxing. Which in turn gets the air squeezed out of him by the way she's hugging him, but he'd be a crappy hero if he couldn't take a hug. Even from someone as strong as Annabeth.

He pulls away a little, just enough so that he can kiss her forehead. He pauses for a moment, considering, before a smile flickers across his face. Percy kisses her nose, her cheekbone, the opposite cheek itself; short, quick gestures of affection before he finds her mouth, easing his lips gently over hers. "Love you," he mumbles.

They have this. And they will always have this. There's no other option.