The Doctor is very particular about his kidneys.
A saver of worlds.
"Because every time you see them happy, you remember how sad they’re going to be, and it breaks your heart. Because what’s the point in them being happy now, if they’re going to be sad later? The answer is of course, because they are going to be sad later.”
I’ll be a story in your head. But that’s okay. We’re all stories in the end. Just make it a good one, eh?
The Eleventh Tribute: [2/3] Speeches
"Hey. Do you mind if I tell you a story? One you might not have heard. All the elements in your body were forged many many millions of years ago in the heart of a faraway star that exploded and died. That explosion scattered those elements across the desolations of deep space. After so, so many millions of years, these elements came together to form new stars and new planets. And on and on it went. The elements came together and burst apart, forming shoes and ships and sealing wax and cabbages and kings. Until, eventually, they came together to make you. You are unique in the universe. There is only one Merry Galel. And there will never be another. Getting rid of that existence isn’t a sacrifice, it’s a waste!"