Time from time Dean get his bad days when everything seem extra dark but Cas is always there to help him, always by his side and somehow together they pull Dean out of the darkness.
But Cas get his angel days too. They are bad, really bad, but no matter how bad they get, Dean stay by his side, offering his whole soul to Cas just to calm him down and bring him back to earth.
And then there are times when the bad days hit them both at the same time. In these days everything can go so many different ways.
Some times there are heated arguments that end with slammed doors and not talking for days.
Other times there are still arguments but they end with angry making up sex, leaving them with ripped clothes and bite marks all over their bodies, passing out right after.
Then there are the worst ones, where they both are just too broken to speak, too broken to do anything, so they just press together and let their tears run down their cheeks, simply letting it all rush over them.
But after all these days, they always come back to each other, always stay together no matter how bad the past days have been.