I watched the show from season 1 (though I haven't seen the last couple of seasons that I plan to eventually catch up on) and let me just say it was unthinkable back in 2005, or even by the time Cas showed up seasons later that one of the main relationships would develop like this. I remember wondering if Cas was going to show up for more than 2 episodes! Times have changed.

(To me, it's especially interesting since the creators / actors were some of the first people who were casual about fandom and shipping. They made a lot of current ways of interacting with a fandom base popular)

Anyway I just wanted to say that even though I'm not in fandom right now, I'm excited by the idea of this episode. (I haven't seen the episode yet, and blocked the spoilers once I realized there were spoilers to be blocked, so I'll find out how I feel about the actual thing later)