The Queen Lived
In Pompeii, in Rome and Sumer, anywhere they could still touch God, they celebrated the hieros gamos, the sacred wedding. Take on the garment of a God, channel and bring him into you, and by union with a human you provide fertility: for yourself, for the land and for the people. You save the world. The Sumerian Kings would lie with Inanna's High Priestesses. St. Theresa built a ministry on it. The Wiccans play it out, every spring, with their daggers and their chalices.
But in all this truth, the oracles couldn't see the volcano. The Pyroviles -- that's who was orchestrating it -- had stolen its power, and were ready to build an army. There's nothing the Doctor hates more than armies, so he realized he had a choice. Or more properly, you had a choice: set off the volcano, naturally, invert the system and destroy Pompeii... Or let the world perish in fire. "If Pompeii is destroyed then it's not just history. It's me. I make it happen." He was infecting you, even then, wasn't he? Like huon particles in a coffee cup, making you special without you even knowing it. Taking what was already there, and adding something else. Something he had no right to add.
And you were returning the favor: you called to him, of Gallifrey, that perished in flame. "Don't you see, Donna? Can't you understand? If I could go back and save them then I would, but I can't. I can never go back." And if you cannot save the world, you said: "Just save someone." And so he did. And your name was written in the stars, and in the household crèche. The first monument, to the Doctor and Donna, was born of that choice. Your memory is spread across the universe, Donna. That's how special you are. I am only telling stories.
The Ood Sphere. A planet of beings so calm, so united, so peaceful and weak that they're born with their brains in their hands. They sing unendingly, in brilliant harmony. Holding nothing back. The libraries in which you and I spend our time, our selfish little stories: they'd never comprehend that. Not until the Second Great and Bountiful came, and took away their songs.
He knew you didn't want to hear the songs that were left them, but you insisted. And he put his hands against your head, like a father to a blessed daughter, like a husband to his holy bride, and showed you the truth of the world. The broken songs of their hearts broke yours, and you begged to retreat. Back into the library, back into the selfishness, away from their pain. You weren't built for this; for the pain inside of everything. For the everything inside of everything. But he was. That's his story, and yours. "I spent all that time looking for you, Doctor, because I thought it would be so wonderful out here," you said. "I want to go home." You already were.