"Today" is an incredibly arbitrary term.
When there are an infinite number of todays across the ever-expanding universe, the Doctor always thought it was ignorant to stamp a hollow explanation on something that has bottomless significance. The Doctor misses the possibilities, the magic of today.
But he knows he'll never get to see another tomorrow, or even another yesterday.
And while today is still an immense, magnificent being, he can't help but feel that in comparison to all the other days he's lived, this one somehow became a little smaller.
Because today is the day the Doctor finally ends.
He isn't sure what happened, his mind is uncharacteristically foggy and his body, while appearing to be physically fine, must not be faring as well on the inside. He's lived hundreds of years, countless numbers of lives.
He knows what it feels like to die.
"Die" is another word he doesn't like. But he knows this is his last life and that there will be no new regeneration, no new him.
Even Time Lords have an expiration-date.
And that's what had scared him. He had tried to run too fast, do too much, burn too bright.
He doesn't have a plan. He knows that he can't depend on someone bursting in to save him. He knows that even though time can be rewritten, he can't run from his eventual end.
Is this what acceptance feels like?
And so as he slipped in and out of consciousness in that impossibly bright white room he thought of the brilliant flashes of color that followed him throughout his lifetimes. He thought of Amy's fire and Rose's glow because the Doctor might have to leave, he might have to lie, but he would never, ever forget.
He cried and he laughed and he screamed as he thought of robot dogs and blue boxes and confessions that were left unsaid.
The Doctor thought of all the separate hims and all the fantastic stories as the sheen on his forehead grew. And while his light flickered, he thought of how part of him was still saving the universe, still going on adventures with two red-heads in wedding dresses, still holding hands with the girl he loved.
And while he closed his eyes and time went wibbly-wobbly he thought of how death, while inevitable, was not absolute.
I originally submitted this for a Doctor Who fanfiction contest (I didn't win) and I figured I might as well post it here so more people could read it. Hopefully someone out there enjoyed it. Input, as always, is very appreciated. Thanks for reading :)