It starts from the pale underside of Dean's forearm - the Mark of Cain glows a soft red, almost seeming to breathe in time with his rapid pulse as he watches it. With each beat it gets brighter, hotter, angrier. The jawbone falls from his hand to rest next to the knight of hell it has finally slain, and both lie still and forgotten as the red light spreads outward from the borders of the mark in long, twisting veins, like bolts of lightning forming streaks and grooves in Dean's skin.

His breaths come out fast and heavy with panic as the light rips long, wandering trails of pain up Dean's arm and over his shoulder. Rivulets course down his back and chest and he can almost take it, until they hit the sensitive skin on his neck, ad his vision swims.

"Dean!" Cas shouts. He sounds like he could be a thousand miles away.

He's not too late.

For Cas, time is one of the strangest things he'd had to adjust to as a human - the constant beat and inevitability of it - he had missed this, the ability to stretch a single moment, to consider all angles and view all possibilities, and he feels fortunate to have it now when he sees Dean's knees start to buckle.

Apropos of nothing, it is Hester's voice that he recalls. When Castiel first laid a hand on you in Hell, he was lost! Hester had been right, of course. He had been lost. But what she didn't understand, what she could never understand (Dean would say that angels didn't have the equipment to care) is that he had just as much been found.

He does not envy Dean the weights that come with human love, the anxiety and fear and confusion. Castiel is unburdened by these things in his love for Dean. He feels no pressure to change it, to examine it, to label it, to speak of it. These things are artifacts of humanity, and he would indulge Dean, if Dean were ever to feel such needs, but the experience of love alone is enough for Castiel. It always has been, since that moment when he first touched Dean's soul and he knew.

The truth is that he'd never expected for Dean to have this kind of feeling, a love like links in a heavy chain to drag behind him, a burden that by all means he doesn't think Dean should have to bear.

In the frozen moment, he slips his hands into his pockets. The raindrops, hanging stilled in the air, part before him as he walks across the pavement until he stands inches from Dean.

Dean will not like this, he thinks. But while he could stand in this frame of time for eternity, for Dean, there is no time. No time to explain, to let him know that this is necessary, that it is the only way forward, the only way he can be saved.

Like something from a human fairytale. It could be funny, if it wasn't so personal, a kind of humor that only recent experiences have taught him. He supposes the original tales always were a bit grisly.

Time begins again, the rain falls, and so does Dean. Cas is already there, catching him, holding him up. One hand is splayed against the flat of Dean's back, and the other grasps broadly at the back of Dean's head and mashes their mouths together. The strength given to him by grace keeps Dean from slipping or pushing away.

And he does try to push away. By the time he realizes what is happening, their lips are already pressed tightly together. Dean's pupils are blown, his brow is furrowed, he pushes against Cas' shoulders in a struggling portrait of confused astonishment.

Until he doesn't.

Until the pain like knives inside his skin begins to recede, and a long sigh of relief escapes his nostrils and his eyes flutter closed. It feels wonderful, and before he knows it, his hands are not pushing, but grabbing fistfuls of trench coat and pulling them tighter, wanting more.

The light comes, so bright Dean can see it like the sun through his eyelids. It starts between them, where their lips meet, and it spreads until it engulfs them both. It meets the red in Dean's flesh and pushes it back like cool water on a burn, healing everything it touches.

And as suddenly and violently as it came, it is gone.

Simultaneously, they pull apart. They gasp for lost breath. Neither takes his eyes off the other, inches apart and searching desperately for answers. Cas braces for Dean's anger, but it doesn't come. Dean is unreadable, his eyes like shining green error messages as he tries to process the new information.

Cas had saved him.

It had worked. Specifically, it had worked when he responded.

Dean puts the puzzle together and tries to keep his face neutral when he realizes what it means, what's out in the open now. He isn't sure whether to be panic or be relieved at last, trapped in an emotional nowhere-land, a place he cannot define.

"Dean, I'm-" Cas almost says he's sorry, but he doesn't, because he's not. He settles on something more accurate. "I did what I had to." He doesn't take his eyes off of Dean's, not for a second.

Dean lets his eyes fall shut. He sucks in a long, slow breath and lets it out in a voiceless laugh. So many questions, but his mouth won't form even one. He supposes he never was one for the emotional talks, though he wonders if he might need to overcome that at some point, dealing with this, whatever this is. But whatever is to come, it is for another time.

For now, his palms come up to cup against the line of Cas' jaw. He draws in slow, watching for any slightest sign of resistance, but there is none, and their lips gingerly meet in the memory that Dean would rather keep.

Cas' hand tangles in Dean's hair, soft and almost tentative this time as he feels the hesitant thrill that marks the bold line he now crosses hand in hand with Dean, in what feels like the most natural next step in his education in free will:

The line between I did what I had to, and I did what I wanted to.