Gabriel fiction
Gabriel finds him after they loose.
It didn't end like he thought, Sam never said yes and neither did Dean, destiny just stopped waiting one January morning, so Lucifer and Michael burned through the world, the energy bursts erasing most of their Father’s living creation on the way.
Castiel's vessel is also dead and the only thing stopping it from crumbling to the ground is his grace, and even that isn't going to cut it for much longer. Gabriel tells himself that's why he coaches his little brother to come fly with him, but the moment he sees Castiel's true form, with most of his being black from grief, he knows it's not.
Misery loves company, and even if they aren't grieving for the same thing, (because while Gabriel never figured out how to love anyone more than his brothers Castiel had) atleast they're both feeling the same, unlike the rest of the angels celebrating Lucifer's final fall, without caring that Michael followed Lucifer to spare himself another millennium of loneliness.
They’re flying over what used to be Sweden when their wings touch briefly, and suddenly both of them are ravenous, they plummet towards the snow cowered ground while clinging to each other blending their graces like mating couples except that they’re not.
No matter how desperately Gabriel’s grace call for Castiel’s his is screaming out for another name, and they end up tumbling together with snow melting around them, and Gabriel constantly bleeding power into his brother so that Castiel won’t burn himself out with despair.
Gabriel curses their Father.