She hadn't been able to sleep. Hours of tossing and turning had led to Rose going for a walk, and ended up with her leaning against the railings in front of the TARDIS control panel. She stared, half dreamily, at the controls that had seen the Doctor running backwards and forwards in front of them a few hours previously.
The Doctor. She'd lost count of how long she'd been travelling with him. It felt like lifetimes. She was a different person from the girl that had walked through the door of the TARDIS for the first time. Then again, so was he.
That was the thought that had been nagging at the back of her head. He'd already left her once. He'd changed, become someone else. Something in her mind was telling her this was going to happen again. She wouldn't be able to keep this Doctor. Her soul mate. The man who had stolen her heart.
Rose had spent hours and days analyzing the relationship she had with the Doctor. He was her best friend, her brother, her soul mate and the the other half of her heart all in one. He completed her. She was not Rose without her Doctor. She'd been in love before. She loved Mickey. But Mickey got on her nerves sometimes. She missed him, but she liked the time away from him. With the Doctor, she never wanted to be apart from him. She wanted to stay with him for the rest of her life.
"Not sleeping?" Rose jumped at the Doctor's voice. She'd been so lost in her thoughts that she hadn't noticed him. He was leaning next to her, arms folded.
"Not really." she replied quietly.
"Looks like you've got something on your mind."
Rose shrugged in reply. She didn't really know what to say. Instead she leant her head against his shoulder.
"How long will it be like this?" She said, after a while. She felt the Doctor tense, and realised she may have phrased her question badly.
"You're...unhappy?" The Doctor replied.
"No...no, god no, of course not. It's just..." She lifted her head and shifted herself so she was looking at him. "This is the second Doctor I've known. I mean, I know it's still you but...it's also not the you I met." She looked into his eyes. "Am I going to lose you again?"
The Doctor cast his eyes down. "Rose...I can't promise you anything about the future. You know that. I can't promise you I won't change, I can't promise you that you'll be safe." he looked back at Rose to see her eyes shining with tears. "Rose. My Rose, my Rose Tyler." He closed his eyes and rested his forehead against hers. "I can promise you that whoever I am, whenever, wherever I am, you will always be my Rose Tyler." Rose reached up and wrapped her arms around the Doctor's neck. He held her close.
"Rose, if I spent all my time thinking about how I might lose the people I care about, I'd be sad forever. But I have to enjoy the moments I have with people. That's the important thing. Rose, we could have years together yet. Let's enjoy that." He held her at arm's length so he could study her face, which was tear stained but smiling. He kissed her forehead. "Now Miss Tyler. Get some sleep and think about where you would like me to take you tomorrow." She smiled, and started to walk off to sleep. Suddenly, she turned back and gave the Doctor one last hug.
"Rose" he whispered in her ear as he held her tight. "Rose, please never forget what you mean to me."
Rose ended up sleeping very well that night. She dreamt of her best friend.