tiny steps at a time
In order for Castiel to complete the spell sending the Leviathans and lost souls back to purgatory his body has to compensate to seal it. This results in him being reduced to a small child with black wings sprouting from his back.
This is story of when the Winchesters after a month of raising their bundle of joy leave to go on a short hunt, leaving the ever patient Bobby Singer to look after one year old Castiel. Everything will be absolutely fine.... right?
- Part 1 of tiny steps at a time