AU- Rose chose to leave. Amy was visited by the 10th Doctor as a child, not the 11th.
Also, I don't own Doctor Who, unfortunately

The pain. Oh, god, the awful radiation, coursing through his body, killing his cells one by one. He hated slow deaths. Breath hitching as he stumbled around the TARDIS, he hit buttons here and there.

It hadn't been a goodbye. It was supposed to be closure, seeing his friends one last time. Instead it had left him guilty and sad. Martha, Jack, Donna, River, he had failed them in this incarnation. He had failed a lot of people in this incarnation.

There was still Rose. His Rose. It had been years of his time since she had chosen to leave. She given up her wild life with the Doctor to lead a "normal" life. He checked in on her periodically, always from afar where she couldn't see him. She was the only one, the only one he hadn't tainted with his destructive habits. She was the only one he hadn't failed.

He typed in her coordinates. She lived in a small flat outside of London. The TARDIS lurched for a second as it accepted these directions, then settled with a grating sound outside of Rose's house. He staggered to the door, flimsy plimsolls bumping into various objects. His vision was already spotty, and he felt dizzy and nauseous. It was only a matter of time before his regeneration began...

The night air was cold, unrelenting. He considered knocking on her door, but a large part of him didn't want her to see him like this again. One regeneration was enough to watch. So instead he stood there, remembering his adventures with her, comforted by the idea that she was safe.

Rose awoke with a bolt at the familiar sound of the TARDIS's brakes. Pulling on her robe and glancing out the window, she grinned at the sight of the blue box and the Doctor. She knew that he visited her, when he thought she wasn't looking. She was looking, and this time she was determined to see him. She ran down the stairs as fast as she could. By the time she had pulled on her boots, though, the Doctor was already slipping inside the TARDIS.

"Doctor!" She called after him, dashing across her front lawn. He froze for a second, giving Rose enough time to follow him into the blue box.

"Rose," He whispered hoarsely. "You need to leave."

She stared at him, taking in his pained walking and obvious distress. "Doctor, I'm not going to go." Her lip twitched. "Are you alright?"

He didn't answer. "You need to go, Rose."

"You're dying, aren't you?" He bowed his head and quietly walked to the other side of the TARDIS. "Oh my god." She began to sob. "You are."

"Yes, I'm dying Rose, and with the amount of radiation I absorbed my regeneration will have enough power to destroy the whole TARDIS which is why you need to go right now before I start, because you are not getting hurt! Do you understand?"

"Doctor... What happened?" She asked him softly.

"Rose, you need to go. I'm not-"

Suddenly, the TARDIS jerked to the side. The Doctor immediately began twisting knobs and pulling levers, desperately trying to land the TARDIS somewhere. Rose joined him. "She's taking us somewhere!" He shouted over the din.

"Obviously! But where?"

"Middle of nowhere, seems like-" The Doctor was interrupted again, this time by his own agony. He doubled over, clutching the console for support. "It's starting."

Rose started to cry again. She still remembered his last regeneration. The pain he was in. How different he was after. She stared at her Doctor, her beautiful doctor with his messy hair and his pinstripe suit. He was going to change into someone new again, a thought that caused her more sadness than anything in the whole universe could.

"Don't regenerate," she moaned. "Please don't."

"Trust me, Rose," He paused. "I don't want to go." Wiping a tear, he continued. "It's to late for you to leave, but, just...go hide somewhere. Away from me. I don't want you to get hurt."

"I'm not going to go. I'm staying with you."

By now, the TARDIS had stopped, right above the earth. Everything seemed so small and inconsequential compared to this moment.

The Doctor didn't respond, but he didn't protest either. Instead he walked away from her to the center of the TARDIS and stood there, inhaling and exhaling deeply. She watched as he lifted his hand, internally wincing at the grief plastered on his face when he saw the golden light dancing around his hand. It was starting. The light spread, from his arms all the way to his face. He managed a small smile to Rose.

And then he exploded.

This was far worse then his last regeneration. His arms and face had disappeared into the fire, his screams echoing through the TARDIS. It was at the same time magnificent and terrifying to watch, like a firework devouring the sky. Rose pressed against the wall, one hand over her face to keep from going blind. She could vaguely make out his face through the bright shine, watching as it morphed from his own face into someone new altogether.

The screams stopped. The light around him dimmed. Gone was her Doctor, and in his place stood a young, gangly looking bloke with a flop of dark brown hair. He grinned widely, staring down at himself. "Legs! Still got legs, good! Arms, hands. Ooh, fingers. Lots of fingers." He appeared to be doing a body check. "Ears? Yes. Eyes: two. Nose... I've had worse. Chin- blimey! Hair... I'm a girl!" His voice squeaked. "No! No! I'm not a girl!" He rubbed his Adam's apple. Then, yanking his hair down, he exclaimed, "And still not ginger!"

Rose couldn't help but gawk. Even though she had watched him regenerate before, it was still so weird to see. She knew that it was still the same person (basically, anyway) on the inside, but sometimes it was hard to get past the outside.

Almost as an afterthought, the new Doctor spun around to face his companion.

"Rose! Brilliant, brilliant Rose!" He hugged her tightly. "New me! New body! New adventures awaiting!"

Rose bit her lip, staring at him. "You're different...again."

"Well, that's the thing about regeneration, happens every time I die." His face registered something in hers, a bit of... dejection? "Are you okay?" He asked slowly.

"It's not easy for me, okay? You changed everything about you and," She sighed. "It's hard."

He ducked his head, thinking. "Do you want to go home?" He said after a while.

"No, of course not." She blurted quickly, shaking her head. "I just need some time to adjust, that's all."

He was shorter now, and they could almost look eye to eye. He looked the same age as her. He was very attractive, to be honest, with his mop of hair and brooding bone structure, but she knew they could never be together. The Doctor could never be with anyone.

He clapped his hands together, obviously relieved that she didn't want to leave. "So," He smiled maniacally. "Where are we gonna go?"

Shrugging, she leaned against the console. "Ah... Where ever. As long as its fun." She gave him her 'sexy half grin', but he wasn't paying attention.

He paced to the other side of the TARDIS, pulling a tiny mirror down and examining his face. After a beat he looked again at his body, taking in his lanky limbs and huge feet. "I'm young. Haven't been this young before. Different."

Rose slid an eye over to him. "Your clothes," She gestured at him. "They're, uh, a bit tattered."

"Oh! Yes! Clothes! I need clothes. I'll-"

The Doctor crumpled to the ground. Rose rushed to him. "Post regeneration energy, right?"

"Yes," he said through gritted teeth. "Gotta land somewhere, get an apple."

"An apple? Have you gone daft?"

"I just had a craving for an apple. Ooh, never had a craving before...Good thing I know just the place to find an apple!" He quickly jumped up on his feet, fighting through the dizziness that always came post-regeneration. "We're going to go visit an old friend of mine!"

Rose looked at the new Doctor with a mix of excitement and worry.

Their adventures had just begun.