The Doctor tried to stop Amy reading the next one, and once she had read it, Amy wished he had succeeded. It was definitely what she would call private.
Dear Sarah,
There are so many things I wish I had the courage to tell you. Like how much I missed you; like how much it hurt letting you go. There were so many times when I almost went to visit you, and only just managed to stop myself. I felt so bad for dumping you, and I even sent you K9 in a way of apology, of letting you know I cared. I only wish I could have given you something more than a metal dog.
But as I've told you, I can't ever go back.
Seeing you again after all that time was amazing. Seeing that you hadn't changed, hadn't stopped. Seeing that you were still fighting for what you always had: the truth. But the look on your face when you saw the tardis again, and when Rose said I never mentioned you... it pierced both my hearts. I wish I could explain why I didn't come back, or don't talk about you, because I don't forget, not ever – not about any of you.
You told me that you once fell for a man who you travelled with and after him, no one else compared, and I want you to know that he loved you too.
Only I can't tell you that, not even in a letter. I don't have the courage, even if I wish I did, so I can't even give you this.
I'm so sorry.
Doctor
Amy had known the Doctor had had lots of companions, but he hadn't talked about what had happened to them. It didn't sound like the Doctor to just dump someone back on Earth – she herself considered him her best friend, and she supposed he must have been just as close with previous companions. It made her wonder what would happen to her and Rory – would the Doctor ever just leave them behind?
"Who's Sarah?" Amy asked, apologetic, but still curious.
"Sarah Jane Smith. Journalist. She used to travel with me in the Tardis, but I had to leave her behind when I got a summons from Gallifrey. Amazing woman – fights aliens from her attic in Ealing now." He grinned impishly, evidently delighted at the very idea.
But Amy could tell he was trying to steer her away from the part of the story that he wanted to forget – he was hopeless at talking about personal things, she had noticed.
"What happened?" she pressed, unperturbed. "When you left her, what happened?"
The Doctor dropped his gaze.
"I couldn't ignore the summons, and I couldn't take her with me, so I took her back home. I didn't see her again until – well, she was over thirty years older, and I had regenerated 6 times. It was a complete coincidence, and I was so amazed to see her again. I wrote her a letter, only I never sent it to her. It was after that that she started fighting aliens, and I've seen her three more times since.
"But you could never tell her this," Amy guessed, referring to the letter in her hand.
The Doctor smiled sadly for a second, before leaping up, declaring, "you know what, I'm dying for some jammy dodgers, does anyone else want some?"
So what do people think? Also more ideas for future chapters would be very welcome.
Incidently, I wrote this before I watched The God Complex, so now it seems even more sad and slightly ironic, because The Doctor does leave Amy and Rory behind!