"It's Nothing, ok!?"

He's hurt already, he was hurt before too...

Percy was going to have a cousin outing with Thalia, Nico, Jason, and Hazel in the lake.

He had scars that was in the past, some were from surviving in the demigod world, but his past scars outdid the others.

His scars was shown, he ran away, leaving his cousins with mixed feelings but one was shown in everyone anger, angry to the one who gave those scars to him.

They were sent to the past to correct those. (Courtesy of our favorite Olympian, Hestia!)