"I don't know, but he must do something. Why else would Father have put my name on him?"

Their Father must want him to do something with the boy, but he doesn't know what. Maybe He would tell them, or maybe He wouldn't, but there's definitely something special about Sam.

"You might. Maybe we're here to find them, and then watch over them until they do... whatever it is that they're supposed to do. They're fragile, they probably need the protection. What if yours dies while you're trying to find it?"