It begins during the scene in the laboratory, where he shows up filled with souls and declares himself God. And he tells Sam and Dean and Bobby to bow down in worship for him, and Bobby drops to his knees. He can see they don’t mean it, though, they don’t love him like you’re supposed to love Him.
And then Godstiel gets thinking about how that doesn’t matter, he can MAKE them love him. He can MAKE everyone love him. And he does, and everything works for a while. He has his perfect kingdom, and he fixes everything, and the world works just how he imagines.
Only every time, something goes wrong, maybe he looks at Sam and Dean and Bobby and he knows that the only reason they care right now is because he changed reality so that they would, and so they’re not really them because they’re his own creations, and as an angel he doesn’t have the kind of creative power to make a person with any depth, they’re just two dimensional images of the people whose opinions he cares about, so he goes back in time to that moment in the lab and tries again.
And again and again.
And eventually, they’re back at that moment in the lab, and he’s lived this scene a hundred times over, and he finally says, ‘Stand up. There’s no point if you don’t mean it.’ And events after that play out pretty much how they do in the show.
“Cas, come on, snap out of it, you’re killing people!” You said shaking your head in disbelief. He was definitely far from the sweet angel that you knew now… He was a monster. The kind you usually put down.
“So?” He said with a smile that made your stomach churn.
“Damn it Cas. It’s taking every ounce of me to not… not…” You stuttered.
“Not what? You really are wasting my time.”
“Not slap you round the face you arrogant little shit.” You felt your eyes go wide at your small outburst. With Cas in this state, who knew what he could do?
“What a brave little ant you are, but you know what more evolved species do to ants?” He rotated his foot a little in emphasis.
“I’m not an ant.” You half snarled as you carefully reached into your pocket for any form of weapon.
“Hm. Maybe not… However, I’m God and you, Y/N, are a nuisance.”