2. He's not really 900 years old. He's closer to 1400, but with all the time-crossing, human-changing, exiled moments, he figures he can just estimate and round down. It's not as if 900 is any less impressive or intimidating to anyone he might tell.
3. Romana would know his age. That's the only reason he doesn't miss her, actually. She'd give him away in a heartbeat. She was always so good at that. Frustrating and endearing all at the same time, that was Romana. She was one of his forced companions---one he didn't really want to travel with, and yet when she left, it broke his hearts. He never talks about how much it hurts him, but the TARDIS knows.
4. He always takes the companions home to meet the TARDIS before he invites them on board. The TARDIS was always a better judge of people than he was, and she would always let him know when it didn't think someone was a good fit.
5. Of course, she thought Rose was going to be a terrible fit, and he ignored her. She was more than just a pretty face and blonde hair (which the TARDIS figured would only cause trouble). He thought that Rose would grow on them both and she would help them open up to new people. The TARDIS thought she'd be a menace and steal him away. He was right, and the TARDIS was wrong. It's probably the only time the TARDIS was wrong.
6. The TARDIS regrets being wrong. It should've given her the benefit of the doubt, it thinks. Should've spent more time simply enjoying her company rather than setting off alarm bells in the Doctor's mind. It shouldn’t have mattered if the Doctor fell in love with her, the TARDIS should've just let it happen, it believes. The Doctor, however, can't blame anyone but himself for what didn't happen with Rose.
7. The Doctor refuses to let himself fall into regret. Over anything, actually. It's too easy after everything he's been through. He focuses, instead, on fixing his TARDIS. Showing her that he's not going anywhere, that he still cares. She can feel his pain and he wants her to feel comfort. His human companions are often neglected during these dark moments.
8. He does, on occasion, let himself remember. His eyes grow wet and his hearts clench up, but he never goes so far as to actually cry or let his emotions take over. Too much at stake. When he goes so far as to remember in front of his companion, Martha's hand will slip into his. Every time, he thanks the TARDIS for suggesting he take her along.
9. But Martha leaves him, too. She kisses him on the cheek and tells him that her family needs her and she's gone gone gone. He stares at the door and watches her go. All he wants to do is beg for her to come back.
10. She won't, of course. Because, in the end, the Doctor has to be alone. It's his most painful secret, but it's one he can't make himself forget.
Muse: The Doctor (Ten)
Fandom: Doctor Who
Word Count: 576