A Nephilim. The child of an Angel and human. The stronger the angel, the stronger the Nephilim. Some even grow to be stronger than the Angel themselves. Nephilim are known to be the most powerful entities in the universe. So when Castiel got an alert that one had just been born, he was quick to get Sam, Dean and Jack.

Sam thought the kid deserved a chance. Just like Jack. He was able to convince Dean, with Castiel and Jack’s help, to give them a chance.