"Hunting, training, setting up camp, that kind of thing," Thalia said with a nod. Now that she wasn't talking about her father, she was cheering up a little more. "There's pretty much never an end to the monsters. See, they don't get killed like everything else. You just send them back to the Underworld, and it takes them a while to get back out, but they get out. So we hunt them down."