AU: The Doctor and Ace had lost each other in the Gamma Forest. Suddenly he was summoned to Gallifrey to fight in the Time War, without even getting to say goodbye. Bitter from losing Amelia Pond, he finally returns to the forest only a moment after his seventh incarnation had left her. He lies to her - saying that he was shot in the forest and has just regenerated. It hurts less than telling her how long it’s really been for him.