Disclaimer: Not mine.

Castiel wishes he'd never learned how to feel.

The young, newly-created version of himself (although the fledgeling Castiel had had no concept of gender) had felt, of course - but millennia of training and re-education had drummed that out of him. Feelings were useless. His allegiance must be to Heaven and to his superiors, and anything that could compromise his loyalty must be eradicated for the good of all. Castiel was the perfect soldier. He didn't need feelings.

He always obeyed orders, so when he was chosen to be a part of the mission to retrieve Michael's true vessel from the Pit his first thoughts weren't of fear or danger, they were of unquestioning obedience. What do I have to do?

He would complete the task, and he would move on. He would forget.

Except when he laid eyes on the righteous man's soul he forgot how to forget.

He'd hacked his way through hoards of demons, felt his wings burn up in the fires of Hell, and the only thing that had stopped him from aborting his mission was that he had orders to retrieve this insignificant soul and restore it to an insignificant body.

But once he reached it he knew his motivation for the return journey would be different. He knew he would gladly fight - to the death, if necessary - to protect this soul.

It was perfect.

He carried it out as though it were something precious (which it was - except he'd only expected it to be precious to his superiors and would never have dreamed, if angels could dream, it would mean so much to him so soon if ever) and returned it to the body that would some day be controlled by another.

And he felt the first stirrings of something that a human would label as regret when he realised this. Somewhere, deep down, a part of him protested that Dean Winchester (his higher centres couldn't put a name to the soul, but that changed nothing) should remain in charge of his own body.

That part was quickly silenced.

Except it wasn't.

Slowly but surely, over the course of many interactions (most of which followed a predictable pattern of angst and annoyance), Castiel became more and more set against the idea of Michael inhabiting that body. Dean is the sole property of Castiel, he thinks sometimes when he's certain no-one else is listening, and has been ever since he gripped him tight and raised him from Perdition. He bears his mark, and the only angel in Heaven with any right to take Dean as their vessel is Castiel himself.

That is not a right he would ever want to exercise.

He doesn't want Dean as his vessel.

He wants Dean as his mate.

And that was the point where Castiel (Cas, part of him corrects) realised he has a problem.

Dean is so young, so fragile, in comparison to the seraph. Cas could destroy him without even trying. He promised himself he would be gentle - but that wasn't even half of the issue at hand.

Angels mated for life, and although their bond hadn't been cemented (and Cas often had the horrible feeling that Dean would never return his affections) it was still there. Cas would never be able to choose an angelic mate. His only chance of ridding himself of the all-consuming desire would be to cut himself off from Dean Winchester entirely before anything could happen between them.

There was no guarantee it would solve anything, and as the human's guardian angel Cas would have no choice but to make contact occasionally.

Even if he could do it he wouldn't have wanted to.

Without even meaning to, the seraph Castiel had fallen in love with a human. Dean was always there in the back of his mind, wherever he was and whatever he was doing. He wanted nothing more than to keep him safe. On occasion he would wonder what else he could use Jimmy Novak's body for (he was under no illusion of what his true form would do to the mortal), but this happened very rarely.

The other angels could not be allowed to find out.

They found out. They always find out.

They'd always seen Cas's feelings for Dean as weakness, but once they realised the depth of them they could not be tolerated.

Cas is extracted, painfully, from his vessel before he can tell Dean what he needs to know.

He is beaten, tortured, and killed a thousand times over without being allowed to die, and through it all he is told you do not love him, you cannot love him, Castiel. He cannot love you. These feelings will destroy you. They will destroy us.

And Castiel finally listens.

He feels nothing.

Dean Winchester is merely an assignment, nothing more.

(The part of him that is still Cas, the devoted protector, feels differently. Cas feels.)

It doesn't take too long for doubt to creep back in, or for those irrepressible feelings of longing and love and want to crash over him once more. The rest of the Host do not tell him who to serve. Not any more.

Cas (not Castiel; he no longer feels so much like a Castiel) would follow Dean to the ends of the Earth. He would follow him to Hell and back. He already has. He loves him.

He knows Dean doesn't feel the same, but he hopes.

And in the meantime he knows that Dean considers him almost a friend. It's not nearly enough, but he feels warmer inside than he ever remembered feeling before.

It's a warmth that burns like hellfire, and that beautiful, shimmering sliver of hope will be the thing that destroys him, like the others had warned.

And Cas wishes the pain wasn't quite so addictive.

My first work in this fandom, so please be nice. I don't hate on your work, so please extend the same courtesy to me. (Sorry, I'm just super paranoid about haters right now)