Little:
(And this is an example of turning two lines of dialog into the most depressing thing put on paper [or computer]. Set in 'The Power of Three' when they're all in the TARDIS, after the Doctor decides that he can't stay.)
"What you do isn't all there is."
Of course, it's not. Why would anyone think that it is? Why would anyone want it to be? Why would anyone hope that this is all there is?
Rory looks almost angry at his choice of wording, and he's not really surprised. He doesn't want this to be the only thing there is. The constant travelling, the never-ending running. The shock that he can never seem to reach the finish line. The pain of fire that follows him everywhere he goes. He knows, he hopes, that this isn't all there is.
After centuries of this being his only option, it's all there is for him. And sometimes he forgets that his companions have lives too. Lives beyond him. Lives in one place, one time. A life that he can never earn, no matter how hard he tries.
This life is all that's left for him. Any chance of anything else was lost the same day as his world. He knows what his future will be like. He'll be alone, travelling through the universe and saving things. He'll destroy worlds, commit genocide. He'll kill people, destroy the lives of countless innocents. He'll fight the evil of the universe, and he'll try to save the good.
He'll find new people to travel with, and he'll lose them.
In the end, he'll die alone.
He'll die away from the world that he used to have claim to, that wanted no claim to him. He'll die far away from the people that call (called) him family. He won't die a hero. He'll die the same man that he is now.
Evil.
He'll be lost on some random planet saving random people who he's never even met. They'll forget him, just like they forgot the rest of his race. They always forget.
The great and bountiful Time Lord race will die with him.
Maybe he'll finally destroy the Daleks. Maybe he'll have beaten every last Cybermen. Maybe he'll have stopped the Sontarans. Maybe the Silurians will make peace with humans because of him. Maybe there'll be no more Weeping Angels.
It won't matter when he's dying. It won't matter when he's alone.
He's 1,254 now. Who knows how many years he'll waste doing all that he knows how to do.
Rory, you have options. You have dreams that you can still follow. You have choices.
He learned the hard way in the last hours of his second self that he doesn't. He has no options. His future is cemented for him. It was written in stone, long before he took his first breath.
Humans, they don't have as large a destiny as he does. They don't have the weight of the universe on their shoulders.
The weight that crushes him, always has and always will. With every second, the pressure grows more and more. With each death, he feels himself slip. With each step, he wants to drop it, let it all fall. He's known for far too long that he can't. He's like some sick, true version of Atlas.
In a way, Rory, you're right and you're wrong. This isn't all there is for you. You've got that little job, in your tiny little town, in your tiny little world, in your tiny little galaxy.
And he's got the entire universe, all of time and space to run in.
He'd give it all up for your tiny little job, Rory. He'd give it all up to be human, if just for a day. To rid himself of the pressure. To lay down the weight and say "I've done enough."
"I know."
(Sorry about the late update. Just finished planning a novel [another, I know. I'm bad at sticking to them] and I finished the Prologue today. Yay for progress! But, as long as I'm stuck to this story I'll be updating slower. Every other night I'll write a shot instead of every night.
Review if you like reviewing, I guess.)