Six requested a bit from 'Paying Up,' and here it is. :D Take a look.
He was babbling in his own head, the Doctor realized, and he was stalling. He knew exactly what was waiting for him outside the TARDIS doors. Across the way his first regeneration was having a lively discussion with his current companions. Susan was demanding answers (but she kissed you grandfather! Who was she? Where did she get a TARDIS key?) and his throat tightened when he let himself remember her-her black hair and brown eyes that looked so much like his had when he was young. Barbara was berating him (What kind of an example is that to set for Susan, kissing strange women left and right. You've only just been engaged, Doctor. Remember that Aztec woman? What was her name? Never mind, of course, that Rose had kissed him and not the other way around), and Ian was watching the scene with an expression of bemused amusement.
I watched ‘The Aztecs’ in preparation for writing this fic, and it was quite an experience. I enjoyed it, and watching the Doctor get accidentally engaged was mildly hilarious. It’s not just Ten, y’all! Even One was doing it! And isn’t that a thought? But I believe that he’s always the Doctor to Rose, and with a bit of adjustment she could get used to him as an old man.
I really need to watch more Classic Who. I did like the dynamic between Ian, Barbara, Susan, and the Doctor, and I wanted to get that across here. They were a family: Barbara was the mother figure, Ian was the father figure, and the Doctor was the grouchy old uncle who was secretly a softy. But when he was accidentally engaged to the Aztec lady (and I’ve forgotten her name, shame on me!) he was most interested in her mind. Rose shows up, and she’s clearly from his future and obviously knows him well-but to hear this young girl (even though she’s not really that young) profess her love for him-it was odd. And of course his companions had questions, but he’s completely clueless as well! Crossing timelines, he huffs, is dangerous business and to be avoided at all costs.
But the eleventh Doctor, who is remembering this, feels a bit of nostalgia and grief because he knows how everything ends up for everyone in that room. He knows that Ian and Barbara get married and go on to have two children and a fantastic life-but he also knows that Susan dies in the Time War, as a result of something he did. And I think he wanted to tell Rose about them, but that he wouldn’t because it hurts to remember them.