"Hades?" Groot loved the sound of that! Mischief was his middle name, if that had not already been obvious from the display of greenery throughout the hallways. And when he saw his friend's eyebrows raise and heard the offer of trouble? Groot was in. Even before he knew what was being formed in Percy's mind, he was in. So much that he pulled away from the wall, leaving the rest of the vines as they were. He could deal with them later... maybe.