I do not own Supernatural if I did Cas would already have an anti-possession tattoo.
All Castiel ever wanted was to do the right thing. All it ever lead to however, was the wrong thing.
Castiel, along with many of his other brothers and sisters, were tasked with pulling the righteous man out of Hell. Being the good soldier he was Castiel would have happily died in the endeavor. However, it wasn't until he reached out and touched the Righteous Man's soul, so bright and pure in the hellish surroundings that he knew they had done the right thing.
Or was it? Castiel now knows that it was heaven that wanted the apocalypse, and Castiel had played a part in almost bringing it about. Now it was because of him that Heaven hounded Dean. After all, he was the one that pulled him from the depths of Hell itself. It was because of him that Sam said yes to the Devil and it was his fault that Adam, the boy who never really had a chance, was now Michael's vessel. He had to make things right. He took Dean to see Chuck to try and stop the fight between Michael and Lucifer and stayed behind in order to give Dean a chance. In that last moment of blinding light Castiel wondered if he had done the right thing.
The Apocalypse had been averted however Sam was still in the cage, something Castiel felt absolutely guilty about. He did everything in his power to free him, and he did, because it was the right thing. At the same time, in spite of his hardships in heaven, Castiel never once bothered Dean. He'd visit him every now and then, but only to observe. Letting Dean live his life, free of trouble, was the least that Castiel could do for him. When Crowley offered him that deal it seemed to be the right thing, he could fix heaven and Dean could go on living the life he always wanted. Becoming God was the right thing as well; how else could he effectively not only fix heaven but the world itself. These were the right things, weren't they?
Castiel had indeed rescued Sam from Hell, but he had not been able to rescue all of him. His soul still remained in the cage, every day becoming a little more broken. The Sam Castiel brought back was hardly even Sam. Dean would have even argued that the Sam Castiel brought back was hardly even human. Castiel got lost in his own lies keeping his deal with Crowley a secret from the Winchesters. All it took was the heartbreak in Dean's eyes for him to know what he had done was not the right thing. Becoming God was worst of all. He had meant well, but the destruction that he caused, the pain it had brought, Castiel wondered why he had thought it was the right thing. With his vessel fast deteriorating he did what he could to fix it. With his last thought before darkness took hold he hoped this was the right thing.
For a while Castiel was not Castiel. For a while he was someone else entirely. This someone else was healing people, helping people, this person was doing the right thing. That is at least until Dean stumbled into his life again and brought with him the real Castiel. The real Castiel knew that he what he had done and took Sam's madness and made it his own. It was the right thing to do, it was Castiel's after all.
However, the after effects of the last time Castiel had tried to do the right thing had not yet faded. The Leviathan were still at large, and in a position to take over the world and consume it. Castiel's madness only hindered the process of stopping them. When Castiel was finally able to defeat Dick Roman he was sent straight to Purgatory, a seemingly fitting punishment for his crimes, or so he thought. What he didn't expect however, was for Dean to join him there. Once again a victim of his attempts to do the right thing. Castiel separated from Dean in purgatory. It was the right thing for them both he thought.
Castiel watched as Dean vanished into a flash of blue light. Castiel breathed a sigh of relief. Dean was safe, he was out of Purgatory. He had done the right thing and could feel better serving his punishment because of it. But that punishment was not to last, as soon Castiel once again found himself on Earth. Perhaps he had been granted another chance. Maybe it was this time that he could do the right thing. Metatron gave him an option. An option to close the gates of Heaven. If he could do that, maybe he could end all the bickering and destruction of his siblings. After his previous actions it seemed to be the right thing, to save his siblings from themselves.
Once again however, Castiel was proven wrong. He saw the pain in Dean's eyes, the guilt. He hated himself for it and was beginning to wonder if it was ever worth it in the first place, given the wrong over the right he had done. Closing Heaven seemed like his last chance at finally doing the right thing. Yet as he watched as his Grace seeped out of him he realized that once again he had failed. He didn't realize the extent of the damage, though, until he stood watching, helpless, as his brothers and sisters plummeted from Heaven, wings being ripped from their bodies. He knew then that he had gotten as far away from right as he could have possibly been.
Castiel had settled for doing the little things. The little things he could do right. He could pick up litter, share food with a fellow hungry stranger. He had even cobbled together a makeshift shelter for a litter of kittens. He knew that if he could do little things here or there on his way to find the Winchesters he would be alright. He could make it through this and maybe, just maybe do the right thing.
Castiel had made it to the Winchesters. Not only that, but they greeted him with hospitality that they always had for him. After all, as Dean had said, they're family. Maybe, just maybe Castiel could learn from the Winchesters and maybe, just maybe he can finally learn to do the right thing. Then Dean sits Castiel down, "Listen buddy… you can't stay." Castiel turns and takes one last look at the bunker. He can't help but wonder, "Will I ever do the right thing?"
I've been having a lot of Season 9 feels. And a lot of Cas feels. This is how I deal with them. Good news is a happy chapter of Of Pie and Angels will be up soon.