Y'know, something just occurred to me. We still don‘t know why
Cas keeps being resurrected when he dies (other than lazy writing
and rash plot choices that need to be undone). What it it‘s the
bond he has with Dean? What if during Dean‘s rescue from hell,
during his reconstruction and everything that followed, Cas has
placed a part of himself in Dean and sort of made him his very own
horcrux? And as long as one of them is alive, the other one can‘t
die? I think they’ve never been dead at the same time, have they?
I love this, because many head canons and theories point out that
Cas possibly had to use some of his actual grace (AKA his very
being) to put Dean back together when saving him from Hell. I’ve
always thought that this ‘profound bond’ that Cas mentions at some
point had something to do with this; a tiny part of Cas’ grace still
running through Dean.
So yeah, one of my favorite head canons for Destiel in the earlier
seasons, no doubt about it!