A/N, WARNING: if you hate Martha, do not read this. This is my explanation for the Doctor's behavior towards Martha thus far, which involves Rose, and it isn't a Martha-bashing story, because it isn't her fault Rose is gone. Thanks. Reviews welcome and appreciated: they're what keeps fanfic writers motivated!

Disclaimer: BBC owns everything Doctor Who. This is non-profit fan fiction with no copyright infringement intended.

I hope she understands.

I'm not replacing her. I'm not. I never mean to "replace" anybody. People come and go. I didn't want to lose her. I wish she was still here. But she's gone. And she's not alone. She has her mum and dad and Mickey and Torchwood and a brother on the way. (She didn't tell me, she didn't know. But I knew.) Imagine, Jackie Tyler, a mum again after all these years! Rose will be fine. She always will be.

I can't bear for her to think I just scooped someone else up like she meant nothing to me. It's not true. I imagine her looking at me, bewildered, hurt, saying: "How could you do that? How could you find someone else just a week after losing me?" It wasn't like that. I really did just want to do something nice for Martha.

I hope she understands.

It has nothing to do with her, honestly. It doesn't. It could be anyone right now and I'd be acting this way. Not that it justifies the way I've acted. It isn't fair to Martha, throwing Rose up every day to her, implying that Martha is just a big failure to me. She's not. She's smart and clever and keeps her cool where most people would be screaming their heads off.

That's why I chose her that first day. That look on her face when she saw she was on the moon. I know that look. It's the mark of a good companion. That's how I find them: I see who stays cool in the chaos, who's fascinated and excited even when they're frightened. That was Rose.

I hope she understands.

I'm not good at being alone. There, I said it. I admit it. I bloody hate being by myself. I need a balance. It's totally selfish on my part, deciding not to take Martha back. Well, ok, not totally selfish. She's helpful. But mostly selfish. The TARDIS is big. And not in the "oh my gosh, it's bigger on the inside than it is on the outside" way. No one knows how big the TARDIS is except for me. Nobody can understand how utterly quiet it is, how it's so filled with knowledge and history and power yet so completely silent. I hate silence.

Honestly, would she want that for me? Would she want me to spend hundreds more years alone with only a white hum and my own voice? I don't think so. I think she'd want me to go on, like I wanted her to go on. And yet, I know she'd be upset with me going round with someone else so soon. Humans call it a mourning period. Except that she's not dead. But I still mourn her. But I can do that and not be alone, can't I? And Martha's a good sport about it, for the most part. Except, well… well.

I hope she understands.

I don't mean to be cruel, or hurtful. I think I do it to prove to myself on Rose's behalf that she means something to me, that I… it wasn't business as usual. Somehow I feel like if I know it, then Rose knows it. And that's about as logical as snow in the Sahara, but there it is. I'm preserving the essence of what Rose was.

But I can't keep doing it, I can't. Eventually Martha, or anyone else for that matter, will get sick of it. And leave. And it'd be rightly so, because who wants to have to live in someone's shadow, to walk through the ghost in you? I wouldn't. Martha is her own person, and I have to treat her that way. And that means no more "Rose would've known what to say" or "Rose would've done this" comments. Not out loud, at least. I have to give her a fair shake. I never threw Sarah up to Tegan, or Peri up to Ace. Now, that was a bit different, mind. But still.

So I'm going to remember Rose, and she'll never be replaced. But I'm going to travel with Martha, and she'll be my friend in her own right.

Rose. Martha.

I hope she understands.