Part One
There was a time when being an angel had been enough. He followed the Lord's command and he didn't need anything else. He was simply and magnificently an angel; that was all there was to it. The fact was never questioned and he never needed to be anything more or less. Then, he heard the fateful name of "Winchester". It wasn't much different at first but soon it wasn't enough to just be an angel. Angels didn't have a choice they had God to make the choices for them and they followed his orders. But God was no longer giving the orders and Castiel found himself needing to make a choice. He had to be more than an angel. He had to be human too. Humans were the only creation that could choose their own paths. So he chose and as a consequence of his choosing, he became human.
He was cut off from heaven and his powers dwindled. He began to believe, if only he could be an angel again, it would be enough to help. He felt useless but he stayed true to his choice and was rewarded in the end. God saved him and restored his Grace. The apocalypse was averted and the world saved. He was an angel again wasn't that enough? It should have been. God had finally shown his will, but few were able to see it. Castiel knew his Father did not want the apocalypse to occur, but other, more powerful, angels were still blinded, confused and too short sighted to see that God had spoken.
Castiel, once again, had a choice to make. This time however, the choice called for him to be more than an angel. Last time it was enough for him to be falling and human, now he needed to be stronger than an archangel. Being an angel wasn't enough. So he did what he had to do. He made a deal with the King of Hell, he killed his brothers, he turned away from his friends, he took in the souls of Purgatory, he killed Raphael, and once again stopped the apocalypse. He made a mistake though. He had enormous power and he believed it was his. He believed he had become God. He did not know what else had been lurking in the depths of Purgatory or the power these creatures held. He did not know about the Leviathan. The creatures were subdued at first. Yes, they were strong, but with billions of other souls in the way all clambering to get to the top and assert control, it took time for them to claw their way up.
The Leviathan reached the top eventually. They cast aside the angel and they ruled but it was short lived as the angel with help from the souls took control once more. They stopped and listened as Castiel realized his mistake. Their leader smiled as he listened to the angel decide to put the souls back where they belong. Castiel sought out help and he and the Winchesters tried to send everything back to Purgatory. The Leviathan held on though. The portal closed and Castiel awoke. Before long he was overpowered by the Leviathan. They were in control and even after most of them left, he was still overpowered. He was an angel, he should have been able to take on anything, but he was facing something far more powerful than any angel and Castiel alone could not win. Being an angel was not enough.
AN: This is my first Supernatural story and I'm excited to see what you think of it. I wrote this because I refuse to believe Cas is gone. There's no way they'd kill him off and my guess is that the lead Leviathan everyone keeps talking about is wearing Jimmy's body with Cas still locked inside. This story will have three more chapters at the most this is really just the prologue. Please review if you liked it or have any advice for my writing.