This is my first fanfic, so yeah, it's not fabulous but I hope people enjoy!

Disclaimer: I do not own Doctor Who, clearly.

It all started with a single grey hair.

There had been other things that could have given it away. She had been struggling to keep up with the Doctor lately. There had been occasions when they had been running together, and she simply couldn't go on. She labelled her growing exhaustion as mere lack of sleep, and made an effort to get to bed earlier, rather than stay up late and read in the library or sit and watch movies with the Doctor into the middle of the night. But this made no difference. She had once been able to run miles effortlessly, but now she struggled to go up a couple of flights of stares without stopping for a rest.

Also, there was the laughter lines. They were tiny-almost invisible-but they were there. She hadn't really thought anything about them. She was so happy with the Doctor, laughing and smiling non stop as they discovered the wonders of the universe. It was no wonder it was showing on her face.

But it was the grey hair that made her panic.

A single hair that had somehow escaped the peroxide. She clamped it between her index finger and her thumb, and stood before the mirror, examining it with her eyebrows furrowed. It waved gently when her breath hit it, and it seemed to be laughing at her.

"I'm twenty. How the hell do I have a grey hair?" She mumbled to herself, confused.

Maybe it was something to do with time travel. Could time travel speed up the ageing process? Obviously, it wouldn't affect the Doctor-Time Lords don't age, they regenerate. She thought back to her encounter with Sarah Jane. She looked brilliant for her age, and she'd spent a long time with the Doctor. So, what, was Sarah Jane an exception? Or was there something unusual happening to Rose?

She knew that the only way she could find out what was going on was to talk to the Doctor. But as she thought of the conversation she might have, her stomach felt like it was filled with not butterflies, but angry wasps. What if he didn't want her to stay with him anymore? What if he dropped her back at home, to endure a life of work, chips, and sleep? She knew she wouldn't ever be able to live like that. She knew she wouldn't ever be able to live without the Doctor-despite the fact that she could never tell him why. He would never understand, and the feeling could never be mutual...could it?

She stood there, deliberating for quite a while. The grey hair danced in front of her eyes, and eventually, curiosity won over dread, and she went to find the Doctor, trying to clear her mind of depressing thoughts that seemed to cling onto her mind like glue.

She found the Doctor messing with some dials on the TARDIS console, and looking at the screen in confusion. His brown coat lay sprawled on the captain's seat, and Rose moved it aside and sat down, preparing herself to speak to him. He pushed his glasses back and muttered to himself, apparently about something not making sense at all, but Rose couldn't hear for sure.

"Ahem." Rose coughed loudly, causing the Doctor to jump back in surprise.

"Blimey, do you want both of my hearts to have an attack!" He spluttered. Obviously he hadn't noticed she was there.

Rose giggled at his reaction. He flicked a switch on the console then sat by her side, sticking his tongue out in mock annoyance.

"What doesn't make sense?" She asked, after composing herself and turning to look the Doctor in the eyes.

"Oh nothing. Just timey-wimey nonsense. I think there's some glitch in the inner wiring, should be easy to fix. She's getting old." He sighed, patting the seat.

Rose could tell that this was not the problem he had just been trying to solve, but she let it pass and decided to speak to him about her own problems. She had anticipated sounding intellectual and merely questioning, to ease herself into the conversation, so as not to get the Doctor worried or doubtful. But her mouth decided otherwise, and just sort of shouted it at him like she was insane.

"Doctor, does time travel usually affect the ageing process?" She blurted out, feeling her cheeks grow red.

He hesitated for a bit too long.

"Yes." he replied, sounding unsure.

"You don't sound too sure." Rose asked, annoyed that he seemed to be lying. Had he noticed? Did he already have plans to drop her back at home? "It didn't seem to have affected Sarah Jane. Or Mickey." She said, thinking back to her ex-boyfriend, who had decided to stay behind in a parallel universe. He had changed inside, he had grown as a person, but his appearance had remained almost exactly the same.

"Weeellll, technically no." He said, rubbing his chin and slouching back in his chair.

"You've noticed then..." She whispered, panicking.

"Yes." He nodded, looking at her intently. Hiis eyes drifted to her hair and she imagined that grey hair sticking out like a neon sign.

"Isn't there something we can do? Some sort of medicine or operation or gadget thingamajig that can make it slow down? Or stop? I promised I'd stay with you forever, but at this rate, I'll look 80 by the time I'm 30! And then I'll die and I'll have broken my promise!" The words came pouring out at an alarming rate, tears rising in her eyes as the panic bubbled in her chest.

"There is an age serum, humans actually invented it in 4013. It can stop the ageing process completely. Affects the cells in the body, puts time-restraints on every single cell, causing a biological reconstruction, allowing the brain..." He rambled for a while, then stared at her with an incredulous expression, as if he couldn't believe she'd even bother asking. "But there is no way you're taking it." He laughed.

He doesn't want me.

His words echoed in her ears and hurt her brain. Had he already tired of her? A lump stuck in her throat and she choked out the word "Okay" before running off and bursting into tears with a violent sob, not caring how she sounded like a spoilt child.

She stormed to her room and closed the door, no, slammed, the door. She really did sound like a spoilt brat, but she didn't care. Because the Doctor didn't care. She felt her whole world crash around her; her ears were ringing, her hands were shaking madly and her vision was impaired by a continuous waterfall of tears that now poured from her eyes.

Furiously, she grabbed her belongings and threw them carelessly into a duffel bag, before angrily kicking the leg of her bed with a scream. This only resulted in her falling to the floor, clutching her toe and wailing, adding another pain adding to the onslaught of agony she already felt in her heart.

A quiet knock on the door pulled her back into clear thought, and she hurriedly wiped away the tears, leaving a large black smudge of mascara on her hand.

Clumsily, she pulled herself to her feet, and opened the door a tiny bit, leaning against it and hiding her face.

"What?" She asked in a monotone voice, trying to sounds mutual and uncaring. She ignored the fact that he probably heard her scream.

"Can I come in?" He sighed sadly.

She opened the door and turned away, trying to avoid his gaze in the mirror. He closed the door, and held up a up and mug with a slight smile.

"I brought you some tea." he said.

Was he mocking her? This was not the Doctor she thought she knew. He would not break her heart, and then cruelly laugh at her. Maybe she had got him all wrong.

She stared at him with empty eyes, her mouth slightly open. His hair looked messy, like he had run his hand through it as he often did when he was thinking.

"I think you-" he began, but suddenly his hands shook and he dropped the cup of tea. It fell to the floor and smashed loudly, sprinkling both of their shins with warm tea.

"What-what are you doing?" He stammered, a desperate look of terror filling his eyes as he looked to the bed. Rose turned to see his gaze fixed on the half-zipped bag on the bed.

"Packing." She said without emotion.

"You're-you're leaving?" He stammered.

"That's what you want, isn't it?"

"No! No! Why-why on earth would you think that?" He shouted, grabbing her arm and-a bit too violently-spinning her so he could look into her eyes.

"If you can't wait for me to just die, you might as well drop me off now! Why wait to get rid of me?" She shouted in retaliation, standing on her tiptoes to look him directly in the eye.

"What the?-oh." Realisation dawned on him, and a look of relief spread across his face. He laughed, much to Rose's annoyance.

"It's not funny." She muttered, upset.

"Rose, you can be so daft sometimes!" He smiled, kissing her forehead. Before she could say anything he pulled her into an enthusiastic hug. All her resistance melted as she leaned her head on his warm chest and wrapped her arms around him like it was the most natural thing in the world. He leaned his head on her hair.

"I thought you'd got bored of me." She said, embarrassed at what was probably really her having a massive overreaction.

"I could never get bored of you Rose." He sighed.

"Then why can't I take the serum?" She pulled her head up to look up at him.

"It's not that I don't want you to. I want you to stay with me forever." He whispered. He gently tucked her blonde hair behind her ear and stared into her eyes, making her insides melt. "You're perfect."

He'd said it in a way that made Rose think he hadn't meant to say that aloud. He pulled back with a mortified expression and tugged at his ear nervously, biting his lip, confirming her suspicions.

"What?"

He deftly changed the subject back to the serum.

"There are complications. With the serum. It works differently on every person. Sometimes they stop ageing all together, sometimes it slows, sometimes they can come incredibly ill...and sometimes... they die." An expression of deep thought and seriousness spread across his face. "There's no way to tell how someone will react to it. And there's no way I'm putting you in danger." He said, softer now, stepping closer and gently cupping the side of Rose's face, looking deep into her eyes once more. "I don't want to lose you."

Rose's heart skipped a few beats, but she grabbed the opportunity. She placed her hand on top of his and held it there, feeling his soft skin against hers, smelling his intriguing scent-something like a bizarre but delicious mixture of tea and fresh grass- and and wishing they could always be like this.

"I'm willing to take the risk." She said, almost silently, with a small smile forming on her lips.

And she was.

Please read and review! Do you think I should carry on or should I not bother! Feedback and constructive critisizm appreciated!