There are four separate instances in the new promo for 9x18 where the shots flash from Cas to Dean. In each instance, Cas is awash in warm shades of gold and yellow, while Dean is drowning in shades of sallow green.
The first time this happens, Cas is in his motel room, presumably watching porn on tv, and then it cuts to Dean on the phone. The second time, Cas is in his motel room, going through his belongings, looking at books it would appear, while Dean is seen showering, somberly. The third instance of this shows a close-up of Cas, looking outward at someone, or something. Dean is seen immediately after, staring at his own reflection. The final time this happens Cas is tied up, I’m assuming by Metatron, while Dean is shown beating a captive Gadreel.
I usually don’t put much stock in the composition of promos, they’re typically not put together with that much rhyme or reason other than to tease. This one is…different. It is structured very deliberately, with a voice-over courtesy of Metatron, and each frame fits his narration perfectly. Had the above scenes cut from one to the other only once or twice, I wouldn’t think anything of it, but this happens four times in a thirty second promo. Four times. Each time it is right from Cas, surrounded in warmth, to Dean, drowning in that depressing shade of green, as if the light has been sucked right out of his world.
So what does it all mean? All season long, gold and amber lighting has been associated with Cas. His journey in many ways mirrors Dean’s at present, both of them have taken things inside their bodies, not out of choice, but out of duty, to defeat some great evil. The main difference, however, is while Dean is wallowing in self loathing, doing penance for his perceived sins, Cas has seemingly forgiven himself in a way. He acknowledged earlier this season that what he did in the past does not define him. That is not who he is anymore.
They are on similar journeys, but Castiel is much further along on his. He is in a perfect position to not only be a reluctant leader to his own kind, but a teacher to the man he raised from perdition all those years ago. I am interested to see how scenes with the both of them in this episode will be lit, because I think this may be the beginning of Cas’ golden light attempting to seep it’s way into the dull, sallow green that is Dean’s life.