I tell this tale because there is no one else left to do so. No one to contradict my version of the truth. No need, any more, to hide the secret I swore I'd always keep.

Once upon a time there were two brothers who loved each other. And by that I mean the 'I would gladly lay down my life for you' kind of love. Which they did. Often. Both literally and figuratively. Some people called this an unhealthy codependency, but given the burdens they had to shoulder, I saw it for what it was: a necessity and a blessing. Who else did they have to turn to but each other? Who else understood all that they had to do?

Well, I did, of course. But, then, I'm every bit as much of a misfit as they were. And they recognized that in me. Appreciated it. Drew me into the close circle of their brotherhood.

If you've read The Winchester Gospels, you know the story. Or, at least you know the gist of it. That Dean and Sam Winchester saved the world. That the angel Castiel loved them both, but he loved Dean just a little bit more. And so time and time again he turned his back on Heaven, abandoning eons of strict obedience to the word of God, and adhering to the word of man – one man – instead.

I swear to you that every word those books contain is true.

But they are also filled with half truths. Because the love I felt for Dean transcended the bonds of friendship and family. Because I loved Dean Winchester with a devotion deeper than any love I've ever felt for my Father. Because the very nature of that love was forbidden – a blasphemy no angel should be capable of committing. But I fell into it willingly, knowingly, wantonly...

So God edited this from the Gospels because He felt it took away from His Glory? Because He is a homophobe? Because it didn't make for an acceptable story?

No. None of the above. Publishing the juicy details would have increased book sales. God didn't care if the whole truth came out.

I cared.

Dean was... a complicated man. Some might say broken. But with me he found a way to repair his damaged life. He loved me with the whole of his generous heart and beautiful soul. We loved in all the ways two lovers can come together: physically, mentally, spiritually. We made love whenever and wherever we could: sometimes a furtive, hasty coupling; sometimes leisurely hours of exploration and tenderness that brought us both to the brink of madness.

And no one but God knew of this. Oh, Sam obviously suspected, but he never once was offered concrete proof. Dean and I were very circumspect. We never kissed in public, we rarely touched except for in moments of great stress, and then a hand on the shoulder sufficed. Sometimes, our eyes would meet and whole conversations were held that no one else could follow, though I could sense Sam trying to decipher what was being said. I'm sorry that all too often Sam felt left out, but I will never regret my stolen moments with Dean.

I was the love of Dean's life, but I was also his dirty little secret. What was said and done remained solely between us. I understood his reasons: he did it to protect me, to protect what we had. To keep our love safe we had to hide it away, bury it deep so no one could use it against us. And, yes, this caused me considerable pain, but it was better than not having Dean at all. That was the condition he imposed, you see. Love on his terms... or no love at all.

Dean was everything to me. Of course I couldn't just walk away from the chance to be with him. No matter what it cost me. No matter if he could never know the price I had to pay.

For the first time in my long existence I was happy. We were happy. We built a life together. But that's the thing, you see, a human's lifespan is but a blip on the timeline of an immortal.

Against all odds, Dean and Sam both lived to a ripe old age. But, inevitably, they died. A part of me died too with their passing. The best part of me.

Sam was the first to slip away, peacefully in his bed, as he slept one night. A smile was on his face when we found him, and an answering smile quivered on Dean's lips as tears streamed down his cheeks.

I should have known then: where one brother goes, the other soon will follow. But I was in a state of denial. I told myself that we had not yet run out of time, that things would be okay. And for the brief span of day, it seemed that would be so. When Dean initiated sex for the first time in years, I willingly tumbled into bed, adoring his frail and wrinkled body with hands and lips that had never wearied of him, no matter what form housed his soul.

His last words were the words I never tired of hearing. "I love you," spilled from his lips as his soul slipped through my fingers and began its ascent to Heaven.

It was a double funeral. A hunter's funeral. A glorious pyre that consumed their bodies and my shattered heart. I'm not sure what was said at the service. I know it was well attended by the many hunters and friends the Winchesters had met – and sometimes saved – over the years. I remember Claire was there. She gave me a hug that I was too numb to truly feel. She'd grown into a lovely woman. No longer young. Deep wrinkles creased the corners of her eyes and bracketed her mouth.

"What will you do now, Cas?" she asked. "Will you join them in Heaven?"

I shook my head as I stepped free of her embrace. "I can't," I said. "I struck a bargain with God... and I am bound to Earth."

My service for His silence. A future of eternal, lonely years in payment for His careful omissions in the Gospels.

"Oh, Cas..."

But I couldn't stand her pity. I fled. Returning to the house we'd shared, I packed the few belongings I held of value, and pocketed the keys to the Impala.

And so it began. I roamed the Earth, guardian angel of humankind, helping where I could, keeping the monsters at bay. It's ironic, really. Just as Dean and Sam were before me, I was dragged into a hunter's life by my Father. Unlike the brothers who had each other, however, I had no one.

I wept the day the Impala finally ceased to function, with no hope of repair. It was like saying goodbye to Dean all over again. I gave her the hunter's funeral she deserved. The duffle containing my possessions clutched to my breast, I stood guard as she burned. When nothing but smouldering ash remained, I took a well-worn photo from a pocket and kissed the fading image of the man I'd loved. Still loved.

"Dean," I breathed out on a sigh.

And then I turned and walked away.

I won't bore you with the details of my continued existence. Those exploits have been chronicled in the ever evolving story of The Winchester Gospels. No one can say my Father doesn't have a sense of humour – or maybe it's a guilty conscience? Whatever. In any case, it would appear that the angel Castiel is a Winchester now. It's nice to hear something Dean repeatedly told me, something I couldn't quite bring myself to believe, finally legitimized in print. Castiel Winchester. It has a nice ring to it.

There is no one left now. No one but me.

Humanity had a good run. I did my best to make sure this was so, but I have done all that is within my power. Soon (in cosmic terms) the Earth will be no more, as its orbit inches ever closer to the sun. Already it is an arid wasteland that stretches from pole to pole, devoid of plant and animal life.

I write these words on the final few blank pages of the last existing copy of The Winchester Gospels. They will remain unread by any eyes but mine. They will burn in the coming inferno and blow away. I will sit here and watch them go, as I watched the last ships carry the hopes of humanity off to the stars. My thoughts and prayers go with them, but I am still bound to Earth. And so I pray for the end of the world to also be the end of me.

The wait is interminable. Time is a malicious bitch. I wonder if I will still be sane when planetary obliteration finally arrives.

It suddenly strikes me that I have existed longer without Dean than I existed before I met him. Yet it is the time spent with him that lingers most in my mind. The only picture I had of him is beyond faded now, it is just crumbling flakes of paper. Here the hint of an eye, there the corner of a smile. But the memories that never left me remain crystal clear. I see his face forming before me. The green eyes. The constellation of freckles across his nose. The glow of happiness that lights his every feature when he sees me. The softening of his posture as he draws near to me.

When I close my eyes, I can hear him. That beloved voice. The deep rumble of my name on his lips.

"Cas..."

I can feel the touch of his hand on my shoulder. The gentle brush of his fingers in my unkempt hair.

The scent of whiskey, old leather and cheap hotel toiletries wraps around me.

I taste the tears that roll down my face.

"Cas, open your eyes."

I can't. I won't. It will destroy me. Let this fantasy last however long forever might be.

"I love you, Cas."

"I love you, too," I sob, and against all better judgement, I force open my eyes.

And he still stands before me. Solid. Real. Youthful. Here.

His sweet, familiar taste replaces the salt of my tears as he bends and melds our lips together.

"I've come to take you home," he murmurs between kisses. "Heaven isn't Heaven without you, angel."

I let the book and pen drop to the ground. My hands now have something much better to hold.

"Hello, Dean," I whisper. "I've missed you."