specific dean/cas canon-divergent fic
i read this fic a long -long- time ago, it is primarily dean/cas and it tells the story of them getting together and then all through their deaths (of old age)
some other stuff i remember:
- it was fallen!cas/dean
- sam/sarah as a side pairing
- after cas falls he goes away for a couple of days and then comes back to the brothers -he never speaks about what happened during those days
- when dean dies of old age, tessa is there to take him
- there's a scene where sam remembers cas isn't vaccinated and they have to make up a story of him growing up in an extremely-religious cult to justify it