The first time Castiel met Dean Winchester
The First Time Chapter 01
The first time the Angel Castiel met the mortal Dean Winchester was when said mortal was newly born. Castiel had felt the pull immediately, and knew his new charge had just been born. He went over to the hospital and found the room Mary Winchester was staying at. Hiding behind a veil so the humans couldn't see him and to protect them from his true visage, he entered the room.
Both Mary and John looked exhausted. Castiel whispered in their ears that they'd done well; both parents smiled as they gazed down at the sleeping baby boy in Mary's arms.
Castiel softly touched the newborn's head with his hand to confirm the bond between them. Whenever this child needed him, he could call him, and the angel would be right next to him to offer protection. He couldn't appear in Dean's world, so Dean wouldn't be able to see him, but he'd would sense someone was there to protect him.
The first time Castiel touched the small boy, he knew that there was something different about him, he'd recognized it immediately. This boy was meant to be a guardian.
There were too many people on God's green Earth, and too few guardian angels to guide them and so some special humans were chosen to become guardians. They'd all had one charge unlike guardian angels, for they had many. Their charge would be someone from their family, usually a younger sibling and in their own way the guardian would keep their charge on the right path.
It wasn't often a guardian was born, and so on this special occasion, Castiel blessed the child. In the coming few years he would need to keep a closer eye on the child, for demons would try to take his soul. A guardian's soul was a special soul, and if demons would ever got a hold of one, they'd be able to enter Heaven. When that happens Heaven wouldn't be a save place anymore. God's will would be undone and it would bring forth the apocalypse.
"But don't worry," Castiel told the sleeping infant. "I shall guard you."