All rights for Doctor Who are the BBC's. I own nothing (unfortunately).

Thanks to Russell T. for some of these lines...

"If I could just find the exact combination-" He mumbled, again cutting his arm, "-I should be able to reverse the process."

And how exactly are you planning to do this?

He looked up from his arm to the wall in front of him, doing his best to be glaring at the TARDIS. "I could use the Chameleon Arch."

You know it doesn't work that way.

"I can make it work that way." His voice was dismissive. "All I need is to find the right combination of genes. Reprogramming the Chameleon Arch would be the easiest bit of the whole thing."

You never listen, do you?

He snorted. "You've been traveling with me long enough to know that already." He placed the knife back on the table in front of him and quickly gathered his blood into a test tube. "I know you don't like it," He added when the cut was closed, placing the test tube back on the table. His tone was somewhat more conciliated when he continued. "I know you're trying to take care of me. But if it'll make her happier…"

That's what I'm saying. Feeling his new tone, his TARDIS seemed more conciliated as well. I don't think it'll make her happier. You don't know her the way I do.

"You didn't see the way she looked at me." Pain filled his brown eyes. "You weren't there."

I was, remember?

"I don't mean after I regenerated." He sighed quietly and then sat down by the table. Looking at the test tubes, calculations and plans all over it, he sighed again and added, "She preferred the old me. I'm not sure why... but she did. She still does."

She doesn't care. Why don't you trust me on that? I know her.

"I know you can sense her," He said quietly, "But it's deeper than that. And you can't see everything; even you can't."

You want Rose to tell you that?

"No!" He looked up in panic. "She mustn't know. Swear to me you'll never tell her." The TARDIS didn't reply. His fists clenched. "Swear, now." The TARDIS remained silent for a long moment before reluctantly humming her agreement. He unclenched his fists, allowing his muscles to relax. "Okay, then."

You know that if she ever finds out, she'll be blaming herself for it, right?

"She has nothing to blame herself for." His voice was soft. "She'll know it, too. And if she doesn't, I'll tell her. But at least she won't be looking at me like that anymore."

Doctor-

"That's enough." He gently rolled his sleeve down, grimacing slightly as the fabric touched the still-sensitive skin. "Just don't tell Rose anything about it. Don't lead her here or hint anything or share your worries. She'll be happy with that." His voice was quiet but filled with pain.

You do remember no one has ever managed to reverse a regeneration, right?

He smiled at his friend's last attempt of stopping him as he put on his jacket. "Yup. But it wouldn't be the first time I do something my people thought was impossible." He winked. "Let me know when the analysis is complete."

If the TARDIS were human, she'd have sighed. Alright.

"Doctor!" Rose's angry shout sounded all the way around the TARDIS, making him suspect the ship intentionally amplified it.

He wiped his forehead with the back of his hand before leaning back towards the broken system. There was more than one faulty mechanism in his TARDIS – that's what happens when you steal one from a repair shop, he thought dryly – but the cooling system wasn't usually one of them. That is, until those aliens shot her and it broke down.

"I'm close!" He called back, knowing all too well that it wasn't going to calm his rightfully-angry companion. It's been four days since the system broke, and so far he's had no luck fixing it. He did accidentally stop the water stream to her bath, boil up his own room and anger the TARDIS with numerous little bugs, which didn't help calming either of them down. "I think," He mumbled, activating his sonic screwdriver again. Honestly, this was getting ridiculous.

"That's what you said yesterday," Rose's voice came from behind him, making him turn around. She was glaring at him while holding a burnt piece of fabric that he recognised as one of her shirts. She was still in her pyjamas – the shortest ones she's had – and was clearly unsatisfied by the fact she couldn't go back to the October London outside.

He gulped. "Yeah, sorry about that. I'd try to rematerialize in Jackie's place, but I'm not sure how either of them would respond." Scratching the back of his neck, he added, "Why don't you take my coat? I'll let you know when I manage to solve it."

She shook her head slightly. "No, it's alright." Sighing, she sat down next to him. "Any luck?"

He shook his head. "No. The thing is, there is nothing wrong with the cooling system. But I can't find where the problem is, and the fact it's so hot in here doesn't help." He groaned in frustration. "Heat always messes things up."

She studied him closely for a moment before getting up and leaving. He blinked, both surprised and confused, but his silent question was answered a moment later when she returned with a bucket of water and a few towels. Smiling, she sat back down next to him and placed one of the towels in the bucket. As soon as it was soaked, she used it to gently wipe his forehead.

"Oh," He breathed out in relief as the cool water came in contact with his skin. "Oh, that's good." She laughed quietly and gently moved it over the rest of his face. "How didn't I think about that?"

"You look like a tomato," She said, giggling, before returning the towel to the bucket. He turned his head to glare at her. She laughed again and rolled one of his sleeves up. "I just thought you could use some cooling."

He breathed out again in relief as the wet towel met the skin of his arm. "Yeah," He mumbled. "Absolutely. If only it weren't so bloody hot…"

She laughed again, but her laughter stopped suddenly a moment later. He turned to look at her, wondering why she stopped, the moment she gently touched one of the cuts on his arm. He hissed, swearing inwardly – how could he have been so careless? – and attempted to pull away, but she held his arm tightly, keeping him where he was.

"How did that happen?" She asked quietly, her fingers gently stroking the cut.

"An accident." He attempted to pull back again, but once again, she wouldn't let him. "Trust me, Rose, it's nothing."

"When did it happen?"

"Rose, just leave it alone, okay?"

One of the other cuts must have peeked from under his shirt, because she frowned and rolled his sleeve higher, ignoring his attempts to stop her. Her eyes widened when she saw them all, one after another, each made with precision that even a surgeon didn't have.

"Doctor, what is this?" She asked quietly, horror filling her voice.

"It's nothing," He attempted to pull away once again, this time succeeding. He rolled his sleeve back down, looking away. "It's nothing. Just forget it, okay?"

"No," Her voice was shaking, but she still insisted. "No, I won't 'just forget' it. What the hell is it? Who's cutting you like that?"

"No one. Just leave it."

"No!" She grabbed his wrist, stopping him from moving away again. "Who's doing that to you, Doctor?" He shook his head again, refusing to answer. Understanding the hint, Rose turned to the TARDIS console. "Do you know who's doing that to him?" The TARDIS hummed her confirmation. "Will you tell me?"

"No!" He spoke before the TARDIS could respond. Rose turned back to him, frowning. He swore inwardly again. "Just leave it alone, Rose. Please."

She shook her head, her brown eyes darker than ever. "No. I won't leave it. Not when someone's hurting you like that." She ignored his attempts to shove her away and rolled his sleeves – both of them this time – up, studying the cuts worriedly. Her fingers touched each cut gently, as if she was trying to mend them by touch alone. "Who is it, Doctor? How long has this been going on?"

"Please, Rose." It came out as a tormented whisper. "Please, just leave it."

"How can I?" Her eyes met his, and all of a sudden he could see her pain and concern, overshadowing any other emotion she may have felt.

"I'm sorry," He whispered, gently cupping her cheeks. "It was only meant for good. It was, I swear."

"What…" She took a deep breath, "What are you talking about?"

"I did it." He whispered, again looking away. "It was me. I was the one who did it. To myself. I'm sorry."

She moved backwards, her eyes wide and filled with shock. He could practically hear the questions running through her mind, wondering why he'd do such a thing to himself and how long it's been going on. He knew she'd be disgusted but hoped she'd understand. She'd have to. He was only doing that for her.

"Why?" She managed eventually, her eyes still wide. He refused to look back at her, instead fixing his gaze on the wall in the back of the room. "Why would you do that?"

He shook his head. "Please, can we just leave it?"

"Why did you do that?" She insisted.

"I did it for you," He whispered, giving up. She wouldn't let go; he knew it as well as she did. He had no other choice but to tell her everything.

"For me?" She sounded as if it was sickening her. "How…?"

"Because I thought… if I could change back… you'd be happy." He took a deep, shaky breath. "You said you wanted me to change back. And the way you looked at me… I thought that if I could reverse it…"

"What?"

There was something in the tone of her voice that made him turn his head to look into her eyes. She didn't sound disgusted, angry or anything along these lines. More than anything, she sounded shocked and heartbroken. As if it was hurting her that he thought it'd make her happy.

"I thought-"

"I told you I wanted to come with you," Her voice was filled with pain but soft nevertheless. "I meant it. I wanted you to change back, but that was before I realised you're still… you." Her brown-green eyes were holding his brown ones, not letting go. "I don't want you to change. And I definitely don't want you to… to do that to yourself."

"But…" More than anything, he was confused. "But you said…"

"I would never want you to do that," She whispered, her fingers once again touching the cuts, gentler than ever. "Had I known I'm the reason you're hurting yourself… I'd never have stayed."

"What?" He managed, staring at her.

"I don't want to be the reason you're hurting yourself," She whispered. "I can't-"

She felt responsible for it. He couldn't believe it. The TARDIS was right after all. "Don't leave," He cut her off. "Don't leave, Rose. Please. Just stay."

"Will you stop?"

He hesitated. "I can't…" She looked away, but he could still see the tears glistening in her eyes. "Are you sure?" He mumbled eventually. "I just… I want you to be happy."

"Of course I'm sure." She looked back at him, her tears slowly making their way down her cheeks.

But he wasn't sure. Not just yet. He couldn't be, not after seeing the way she looked at him; after hearing the tone of her voice when she first saw him. His fingers slowly made their way to her temples as he whispered, "May I?"

She didn't even speak. She just nodded. She'd seen him create a telepathic connection with so many other beings, but it was the first time he'd asked her to do that, showing her just how vulnerable he felt and how important it was for him to make her happy. He didn't hesitate; the moment she gave him her permission, he stepped into her mind, searching for any doubt that would prove him right.

"Can you change back?"

"Do you want me to?"

"Yeah."

He couldn't believe she just said that. A part of him knew she would when she asked if he could, but deep down he still couldn't believe it. "Oh."

"Can you?" Even though he seemed to be the Doctor, he wasn't the Doctor she knew. He wasn't her Doctor. She wanted him back; wanted everything to be back the way it was before they ended up on Satellite Five again.

"No."

His pain nearly made him quit searching, but feeling Rose's pain, he knew it wouldn't be right for her. He had to show her he was right – or admit he'd made a mistake, just like the TARDIS had warned him he's doing.

"Now, first thing's first. Be honest. How do I look?"

She studied him, thoughts and feelings running around inside her head, not allowing her to think. He was the Doctor, wasn't he? Sort of. There was something about him that was the Doctor, the same Doctor she knew and loved, but at the same time… "Er, Different," She said eventually, not entirely sure what else she could say.

He studied her seriously, unsatisfied with her response. What on Gallifrey does that mean? He wondered. "Good different or bad different?"

"Just… different."

She seemed to be feeling his disappointment, because she pulled him towards her memories from later that day, when they stood outside, looking at the ship breaking up and the ashes falling down over the earth.

"And what about you?" She asked, heart pounding. She had no idea what she'd do if he wouldn't want her to travel with him anymore. "What are you going to do next?"

For a moment he was taken aback by her question. "Well… back to the TARDIS. Same old life."

"On your own?"

"Why, don't you want to come?"

Relief filled her, quickly mixing with happiness. He wanted her to come with him. He still wanted her. "Well, yeah."

"Do you, though?" His uncertainties were clear to her now, both in his eyes and in his voice.

"Yeah!"

"I just thought, because I changed…"

How could he think she wouldn't want to come? She wanted to come with him more than she'd ever wanted anything else. Even though she wasn't sure about this new face of his at the beginning, she now knew and believed, whole-heartedly, he was the Doctor. Her Doctor.

"Yeah, I thought, because you changed, you might not want me anymore," She admitted.

"Oh, I'd love you to come," He said immediately, smiling happily as his eyes looked at her warmly.

"Okay," She returned him a happy smile, her heart beating happily. It was her and the Doctor again, and as far as she was concerned, no-one was going to break them apart, ever again.

His hands fell away, landing heavily against the floor. He couldn't believe it. All this time he thought she was wrong and Rose wanted him to change back, when she didn't even care. No, he had to correct himself, it was worse than that. She was hurt by the idea she'd have liked him to do that.

"I'm sorry," He whispered, looking up at her. "I thought-"

"I love you," She whispered, not entirely aware of what she's saying. "How could you think I would ever want you to do anything like that?"

"I don't know, I just- What?" Suddenly realising what she'd just said, he cut himself off, staring at her. Did she really say she loves me? "What did you say?"

"I said I…" Her eyes widened as she realised what she said. "I meant-"

"You love me?" No, it can't be true. I must have misheard her. How could Rose Tyler love me? "You do?" He pressed, even though she looked away, clearly wanting to pretend she didn't say that.

"I meant…" She took a deep breath, trying to stop her tears. "What I meant was-"

He didn't let her continue. Seeing how embarrassed she felt about it and how terrified she was of saying those words again, he kissed her, effectively cutting off every other thought she may have had. She was shocked at first, but when his tongue made its way into her mouth, she wrapped her arms around his neck and returned his kiss just as passionately, albeit less desperately.

When they broke apart, the Doctor gently cupped her cheek, his thumb brushing her lips ever so lightly. He couldn't believe any of this was really happening, not any more than she could. Her eyes held his as they looked at each other silently, both trying to grasp the fact the other actually loved them the way they hoped for, the way they didn't dare to think was possible for longer than they would like to admit.

"Will you stop it?" Rose asked quietly, surprising him.

It took him a few seconds to remember what she was talking about, but when he did, he nodded. "I'm sorry," He whispered. "I really thought you'd be happy if I changed back."

"Is it even possible?"

He shrugged. "Not that I know, but it was worth a shot." He scratched the back of his head. "I thought that if I could get my DNA to revert back to my old one, I could undo my regeneration. But it wasn't going very well. That's why I needed so many samples," He added, tilting his head towards the cuts.

Rose shook her head slightly, gently touching each and every cut again. "You needed the blood?" He nodded. "Why didn't you use a needle?"

He shrugged once again. "This was faster. Besides, I needed to see the healing pattern of these cells."

She shook her head slightly in disbelief before gently pressing her lips against one of the cuts. He watched her, wide-eyed and shocked, as she gently kissed each and every incision, touching it soothingly afterwards. When she finished, she rolled his sleeves back down and looked up at him. "You won't do that again, right?" He nodded. She smiled. "Good."

"So long as you'll stay." There was no way he could explain to her how important she was to him; how much he needed her with him. She saved him time and time again, both from his enemies and from himself.

"I'm not going anywhere," She promised. "It's you and me, Doctor. Yeah?"

He grinned, prompting her to flash him her signature smile. "Yeah."

Still grinning, he cupped her cheek once again and leaned towards her to kiss her. At the last second, right before his lips touched hers, they both felt an electric shock sent towards them from the TARDIS.

"What?" Pulling back, the Doctor turned to glare at the console.

HOT! The TARDIS practically yelled at them, making them exchange a look before bursting out laughing. Another electric shock hit them, only making them laugh harder. Noticing she was only getting more annoyed, the Doctor quickly stopped laughing, turning to calm her down before she'd electrify them again.

"Alright, alright, I'm on it," He said, turning back to the console. "Rose- That's it," He cut himself off when she wiped the back of his neck with the wet towel again. "Just what I needed."

She grinned at him. "Now fix the cooling system."

He grinned back at her. "On it!"

It took a few more hours before he finally found the problem and managed to fix it. Once the temperature was significantly lowered – due to the insisting of his TARDIS – he led Rose to the small lab where he worked on reversing his regeneration.

"All out, yeah?" She asked as she started throwing everything into a big plastic bag.

"All out," He agreed before joining her. He didn't need any of those samples or experiments anymore. Rose was happy and loved him the way he was – that's all he cared about. Nothing else mattered so long as they were together.