He adjusted his frock coat and sighed as his aged hands played over the console. It was always so quiet in here, these days. But then it had been for a while now, ever since the great love of his life and his best friend had gone. The corners of his eyes were fraught with wrinkles, both of laughter and of worry, and more than a few tears had tracked their way down his wrinkled skin.
But still he went on, because it's how they would have wanted it. He knew that for a certainty, because they'd shouted it to him even as the explosions came that took their lives. After all, the universe still needed looking after. There were still alien nasties out there, still Daleks and Cybermen on occasion even though they were much fewer and farther between now.
He sighed and sent the great machine into the Vortex even as he adjusted their picture on the console. So much younger they were, and oh how her eyes flashed merrily and him with the perpetual look of bemusement. He'd honor their wish and guard their legacy until Time laid a gentle hand on his shoulder and told him it was alright, he could stop now. He'd go on, saving civilizations and rescuing all manner of people, because that was just what he did. It was all he knew, and it was all he had.
But then, that was always the way of the Last Centurion. He smiled as he thought of the Doctor, of Amy.. and set off to his next great adventure. He gave a soft peck to the picture, returned it to its place and sat in the jumpseat. "Now, let's see what's out there."