Somewhat experimental.
He sits at his window sometimes, finds himself at a loss for anything else to do but watch and wait for nothing to happen. The rain keeps falling, following worn paths on new windows, (replaced from when he was ten), as the rain does, incessantly over the years, although the weather around him has changed. He can't remove the rain from himself, it follows him and clings to him, even when the skies overhead are of the purest blue (he vaguely recalls a gaze the colour of the summer's horizon, a top the shade directly above him when the rain drags him down to the ground, it's the shade he sees so often on these unending summer days).
He feels the wind against his face, only chilled by the rain's presence, and he closes tired eyes to it, letting it, along with errant drops attached to it, ease the feeling of missing, a sort of absence he carries, and for being nothing it is heavy, filled with the rain and the weight of ghosts.
Winds have always eased the weight of that hollow within him, either whittling it down or helping him hold it, the crushing making breathing hard sometimes, and when his chest aches so and his bones remember flight he simply wishes to let go, but he can't. He is too young yet too old, has nothing to fall to, and so he leans to the wind, which obliges his unspoken whispers and makes him feel as though there is someplace to go, someplace he might disappear to one day, when it is ready for him.
It will be ready, one day.
Lighter than ever, he fancifully wishes the wind might support him like they did the ghost but the knowledge grounds him, he is not light enough for that wind to carry him (he is not the weight of a snowflake, a mere breath) and so the windowsill takes his weight instead, pressing against his chest in angular, uncomfortable lines, and it is a hollow reminder of what he is not, the rain rising up against his barriers. He cannot let it fall, breathes out and stares at the rivulets falling around him instead, not from him, and it is a somewhat comfort.
The eternal clatter of those falling drops echoes far into the town, a sound that seems to fill his every moment, become his very voice and summon a solemnity that everyone obeys, heads down and rushing, (he remembers a ghost's frustration at it, a frozen drop in time, a sudden sheet of hail in that moment of freedom, a shared smile) no one takes time now.
Breathing out as far as the rain permits, (he will not expel it from him, he cannot) he wonders if those silent cries ever reach that ghost, so far away it must be that his hand never reached quite that far, only a whisper of a previous presence or a teasing of a frozen smile, never quite there, always preying upon his mind that continues to drown.
He is lost.
His sky's clouds blacken, yet another wave of a gust brings with it more drops, heavier, he can barely hold them, keep them to where they belong.
Boys don't cry.
But then boys don't have ghosts and unstoppable rains and flowing tides sweeping them away, do they. His roots falter, the ground he stands in soaked and not solid enough to grasp him and keep him upright any longer, and on the windowsill, he wavers. Brown eyes watch down, unseeing yet seeing everything, unhearing to the cries below.
The tide is engulfing him, but he is not afraid. To go under would be to be free of the rain no rain underwater, the turbulent waves, the shadowing echoing ghost that exists in the absence. But he wants the ghost to return to him, the exciting frozen ghost who can make the rain stop, who would allow the rain to escape like it wishes, fleeing from its prison.
He doesn't understand which is better.
Already gone, frozen arms catch him as he follows the rain, and take him away, someplace. He wishes for that someplace, he feels it is ready now. He quivers, the rain a following crescendo though he is moving on the winds, it yearns to be freed and yet the barriers are not there, so he releases it. He sees his rain tumble down, visible to the world's eyes, and when he is about to ask is it okay now?, the wind curls around him, a cold warmth, and snowflakes flutter beside his work, a hush filling his mind that eases everything, even the absence he holds, its weight diminishing with every drop that falls, and his lips curve up into a smile, no longer held down by the rain.
You're here, he whispers, and he feels the ghost laugh, placing him down, although now he has the weight of a newly formed raindrop, the winds will carry him, and yet his frozen ghost continues holding him, transcending from ghost to there, and he clings like rain to his window. You came back, he again whispers, fierce in his desire to not leave, let rain and snow mix together for always.
No, his frozen not-ghost says, and he peers into the purest blue and sees the hint of rain in snowy eyes, the vaguest sense of melt-water; you ran to me.
And he had.
A few notes on this: inspired by Esse's 'In the Silence', which is written far better than this but in a similar-ish way. Also the idea that Jack has the weight of a snowflake is all hers, I believe.
I remember seeing a documentary once where it said men who'd emigrated to America from places like Laos became so homesick, they went to sleep and never woke up. One man whose wife woke him up, I believe, said that it had felt like his spirit was flying home. Jamie seems like the kind of person who would never quite be satisfied with simply being human.
I also believe that although the Guardians can be seen, they are not supposed to be seen much, so I imagine that Jack visited Jamie a bit after the events, mostly to check he was alright, and then was forced to stop, although he kept an eye on him.
And more head-canon – Jack wasn't a Guardian automatically once he was born, it seems; he was a winter spirit first. There was snow on the ground before he died, so my theory is that there are other spirits, and namely other spirits with similar powers to Jack's, even if they don't have the ability to make someone see the fun side of life. Hence, things like water spirits and ocean spirits would be not common, but not rare either.
Sorry that it's confusing. But I wrote it to be like that, so… I hope you liked it.