Castiel did not sign up for this. No he most certainly did not. Castiel didn't do 'babysitting' and he definitely didn't do it when the ones that needed to be 'sat' on were Dean and Sam Winchester.
It all started on a Tuesday. Friggin Tuesday. Nothing good ever happens on Tuesday. It was a simple hunt, two demons terrorizing a family, they could easily kill the demons with the Colt. It was a piece of cake. At least, it was supposed to be, until one of the demons ran away. Sam and Dean went after it, leaving Cas to take care of the other demon. That was a mistake. Sam and Dean were taking much longer than expected, naturally, Castiel got worried. He stood up from his spot on the arm chair in the family's home, ready to leave and search for the brothers. Then he noticed the couple and little girl still tied up on the floor.
"Oh… I should probably… Right" He crouched down next to them and untied them all, then he touched their foreheads and they passed out.
Castiel went in search of the brothers, occasionally calling out their names, after ten minutes of looking for them he heard someone yell. It sounded like a child, a little boy. Cas went looking for whoever yelled, Dean and Sam could take care of themselves, this child could not. As he searched he heard that same boy yell out his name.
Cas was confused, how did this child know his name? Finally he found the source of the yells. He was shocked to see a little boy around the age of five wearing clothes that were far too large for him, and another pair of large clothes laying next to the boy, he was even more shocked to see that the boy had a familiar pair of green eyes.
The pile of clothes beside Dean started shifting and gurgling noises were coming out of it. Cas moved towards it and lifted the overly large shirt, he found a baby boy, who couldn't be more than a year old. Cas came to the conclusion that this baby must've been Sam.
"You've got to be kidding me"