The world isn't easy for a demigod, much less easier for a son of Poseidon. He'd get so very stressed out and he'd seek comfort in very odd places, like underwater, in oceans and lakes and rivers. Percy knew where his father's kingdom was, so ever once in a while he'd go down to visit whenever he felt like he was about to burst. He'd go and hug out his emotions with his father and he'd usually end up falling asleep curled up next to his father's side.
"You know," Poseidon said once. "I think you cuddle me more than you do Annabeth."