This might not be seasonally correct with the actual show, I am aware of that, but I don't care.
Chapter Two - Time
Castiel shouldn't be doing this.
He knows this, he knows he shouldn't have done it. You can't change the past. What could possibly be the point, he asks himself, of going back in time, knowing that he can have no effect? None that is good. None that lasts. That's just not the way time works.
God's built-in firewall against the powerful ripping apart the space-time continuum with a few well-placed changes - everything has repercussions.
Save someone today, they simply die tomorrow. Unsink a ship, everyone dies anyway.
Save Mary Winchester...
Something will still come. Something always comes. For Sam and Dean, something will always come. Mary must have felt the same way when she was young, a hunter.
But there was a peaceful time, in the middle, ten good years. Where Mary was a mother, and John was a father, they were husband and wife and they loved and fought and laughed and thought about the future as though it were a million years away. As though they had so much time.
It's sad. Phenomenally, confusingly sad. Which is why Castiel should never have come. Knowing how it all turns out for her. But... the longer he stays, the less he can regret it.
The way Dean's eyes go sad and distant during Christmas time, the way he thinks of her with unrelenting warmth and longing. Castiel had to see her, the way Dean remembered her. And he cannot be sorry for doing so.
Not when he gets to see them like this - daughter and son, bundled in their winter coats and mittens, knit hats and rosiness to their cheeks. The brightness of Dean's eyes is astounding. He really does look... special. Like it shouldn't be surprising that the fate of the world will fall partly on him. He is such a beautiful child. The flush of his cheeks and lips making his orange freckles stand out. And Mary, she is beautiful. She radiates a feminine kind of grace, a strength in her love for her little boy that Castiel awes at, for only barely understanding it.
They make such fun of the struggle through the snow, young Dean very nearly laughing himself out of breath. He takes two handfuls of snow and throws it into the air, staring up into the evening sky to watch it float down again. It glitters in the streetlamp's glow, and he closes his eyes to feel the tiny crystals fall on his upturned face.
He is happy, in a simple way. And it is beautiful.
Castiel looks over to Mary, to see her watching her son. For a moment there is something sad about her, but it is swallowed quickly by the brightness of her affection for him.
When Dean opens his eyes she is there, offering her gloved hand and he takes it without a second thought. Such an oddly painful thing for Castiel to see, the way he takes the hand that reaches for him without any doubt, completely open.
"Will Sammy like it?" Dean asks, looking up at Mary with big eyes.
"Like what baby?" she asks, beginning to move them along again.
"The snow."
"He's too little to play in it yet, but you should tell him all about it when we get home."
"Ok," Dean agrees cheerily.
Castiel stands still, invisible even beneath the light of the streetlamp, and watches them walk hand in hand back to the house where less than a month from this moment, Mary will be taken.
"What're you gonna tell him about the snow?" Mary asks, holding her boy's hand tight.
"Um... how it's sparkly. And, how you can build with it and Dad can make big hills and how when he's bigger we can do snow angels together."
She rubs her gloved palm against his hat-covered head before leaning sideways to kiss the top of his head as they walked.