Dean,

I need to tell you something before I leave – one final confession, if I may?

I'm sure you wonder where I go, whenever I'm not with you. Maybe you believe I've gone back to Heaven, shedding my vessel and leaving Jimmy behind a garbage bin at the back of an alleyway? Or maybe you believe I go to a café in the middle of nowhere, meeting up inside with Zachariah and the other angels, planning the next move to misguide and betray you? Or maybe you'd go as far as to believe that I flee to another one of my other subjects – my other projects?

Let me tell you now that that is not the case. For one thing, I'm not sure there are many people even in Heaven at the moment. For another, Zachariah and I do not exactly see eye-to-eye, as you will soon find out. And finally, I have no other subjects; you and Sam are the only people I see - my only friends, if you will.

You're probably growing tired of reading this. "Get to the point, Cas," you would say if you were here. "It's the end of the world," you would continue, "Spit it out!" All in good time, Dean. Just bear with me on this one.

For thousands of years, I have known nothing but God. He was my father, my companion, my soul existence for living. I worshipped the ground He walked on, and I still do. I would do anything and everything to please Him, no matter what the cost. He was my reason for being.

But over these past few months, something has changed within me. At first I was lost, I was angry – my ambition to impress Him, my determination to push through even the most difficult of challenges started to crumble– I didn't care as much about completing my goals. No, that isn't right. I did care, I cared very much so – but not about Him, not as much as I should have. I cared about you, Dean, cared more about you than I ever believed possible. You were delegated to me; I was commanded to babysit you, to watch over your every move…and there I was, thinking about you when I should have been thinking about Him. You led me astray, Dean, and you didn't even realize it. Here's another conquest to add to your tally of lovers.

I would do anything for you, Dean Winchester. When I first laid my palm on your shoulder, I knew there was something about you that I wouldn't be able to shake off, no matter how hard I tried. And dammit, how hard have I tried to get rid of this feeling! But it's in my bones, Dean, in these very bones that I have inhabited for my own use. The more I tried to forget about you, the more you featured in my every thought.

That is why I am going to do this. You will hate me now, and you will hate me later, and hell, you may even hate me forever. But I have made up my mind. Fuck consequences, fuck destiny, fuck this corrupt and twisted situation where it is all just a game of chess, and we are but the pawns; fuck being a puppet in someone else's game. I am taking control, something I should have done the first time I ever laid eyes on you, and I hope to God it's not too late. You asked me to help you, Dean, so here I am helping you.

I will banish Zachariah. I will teleport you to Sam. I will confront Chuck's Archangel, and pray to my Father that I will survive. It is useless to hope for life, when the wrath of an Archangel knows no bounds - and I suppose realistically, I will not die anyway. To die would be too easy a punishment. When I am caught I will be cast out to Hell, where Lucifer will be waiting for me with open arms. Maybe there I will see you again, someday? I can only sit and wait.

I hope I am not too late, but I am scared that I am. I'm scribbling furiously now, writing as I pace this house, agitation coursing through Jimmy's blood like jolts of lightning. Doubt is my only friend – this is all for nothing, it is too late, Hell will rise to Earth, Lucifer will be released. My only hope is you, and your only hope is me; I fear that if I stop writing, stop to think for just a minute, my resolve will crumble, and I will flee along with my brothers. Even angels have the emotional capacity to be afraid.

I believe that you will not fail, Dean, and I believe that this is not the end of you. God chose you to be saved from Hell because you have a greater purpose to fulfil – you always have, ever since your mother gave birth to you and took you home, right here to this house – to this very room, in fact, where Azazel pushed the ball into motion. You may cast aside this letter in disgust and hatred, but always remember that there is more to you than you believe. You, with your sarcastic comments, dry humour, and that upwards quirk at the corner of your mouth when you find something hilarious but refuse to laugh. You are sacred and you are beautiful. Never change, Dean.

I am sorry.

Castiel