Purgatory really had been the perfect place for Castiel: he certainly didn't belong in Heaven - not anymore, not after everything he'd done - and he had done nothing good on Earth (except for maybe one thing, but it hadn't really been him, had it? It had been two boys and one man, and they hadn't really needed Castiel's help; they would have figured it out regardless, like always).
Hell… Hell would have also been appropriate, but it was for the evil – evil humans, to be specific. Castiel wasn't evil though, and he certainly wasn't human, not really anyway, though he was hardly an angel anymore. Like he had once told Dean, he didn't feel like a bad person. No…
No, Castiel wasn't a bad person; the difference was, Castiel was a monster, and Purgatory was made for monsters.
He should have never been saved. He should have never been set free from Purgatory. In fact, there should have been a cage built just for Castiel, just like there was a cage for Lucifer. Maybe then the angels wouldn't have been cast from Heaven. Maybe then, people – humans - wouldn't be suffering at the hands of his brethren.
Maybe then, he wouldn't have killed – wouldn't have continued to kill - so many of his brothers and sisters…
The angel blade was heavy in his hands and was almost impossible to pull from the limp body of yet another one of his brothers. The blade was slick with blood and cast a red hue as the moon glinted off of its deadly edge. Castiel stared at it for a moment, the acrid taste of bile filling his mouth. He fought down the urge to vomit as the guilt piled up within him. Farewell, dear brother. After each angel he killed, the blade felt heavier and heavier, but for some reason, he kept killing rather than letting one of his brethren tear him to shreds.
Why? Why did he keep fighting? Was there really anything left to fight for? He had rebelled against his family in Heaven who now sought for his head, and the family he had found on Earth had kicked him out. He had nothing left. So why?
Why?
He didn't understand. It was like something within him wouldn't let him die or give up… something so basic… so human… Castiel didn't want to die, or at least, his human self didn't want to die. His desire to live…
It's funny; it was only after losing his grace that he'd just begun to understand humans and their strength. Even though their lives were short, their will to live, their passion for life… they were truly greater than any angel. They were amazing - God's greatest creation. Maybe Castiel would do better as a human than an angel, but he doubted it. Compared to them, he was only an ant.