Dean had sex with Castiel, and it wasen't the first time. When they first met, he had realized that angels were real and that Castiel had saved him. Next thing he learned after their first heart to heart, Dean realized that Castiel wasn't like Uriel, or the usual angels in the garisson. So Dean followed his instincts and showed the adorable, and slightly confused angel a good time, so he would feel better about his doubts. The next time, Dean had sex with Castiel to make them both forget about the apocalypse. And another time to make him stay on earth, to stay with him instead of fight in his civil war. Of course, at that time, it didn't work and he eventually went back to fighting. They stopped having their private times together, when Castiel played God and set all the Leviathans free from Purgatory. Dean thought he made up for those lost times when he convinced a one, Emmanuel, to have sex with him. That conquest was a bit harder than usual, since most the time he kept babbling that he couldn't, because he had to be faithful to his wife, Daphne, was that the name? Eventually he gave into it like Dean knew he would because it was still Castiel, even if he didn't remember that, and he had always bee attracted to him. The hardest was when they were in Purgatory, and they had barely had time to sleep, let alone have sex. So he was running, and bleeding, and fighting for his life and on top of all that, he was repressed. Then he finally got out, and the last time they had sex was to help him get revenge on Naomi, making her uncomfortable, probably watching them. Even if Dean and Castiel have been having relations for about five years, Dean had never thought about what they did together in private as anything other than sex, and a quick way to comfort Castiel. He thought this, until the day all the angels fell. Dean saw sadness, and lost in his eyes and felt the connection with him. Losing family was horrible, and sometimes it just brought people together. This time, when Dean slowly laid Castiel down on his bed in the Men Of Letters bunker, and carefully lay over him, pushing in slowly trying to be passionate about it. He heard Castiel's low moans in his ear and felt his rough hands on his back, blunt fingernails raking up and down. Dean could feel the heat and sweat making a connection between them and for the first time it was making love. It wasn't a quickie and afterwards, Dean lay with Castiel, holding him tight and whispering that everything was going to be okay. He even stayed with him all night. He will keep laying with him, for as long as it takes and he did everything he could to show Cas that he would be there for him, no matter what. He had even taken the big step and told the ex angel that he loved him. Practically ecstatic when Castiel returned the affections, even saying that he always did love him. That was also the day Castiel asked Dean if there relationship could be official. Since then it was, since Dean couldn't possibly say no, with Castiel looking at him with those gorgeous blue eyes.