Author's Notes:
Thanks for reading. Hope you enjoy!

Stepping out of the TARDIS, he looked around.  London was as busy as ever.  People bustling about, cars whizzing by.  Life happening right in front of him.

Twelve hastened his pace, determined to get to the correct spot.  He had about five minutes. 

Arriving with twenty seconds to spare, he took his place.  People continued to pass by him, oblivious to the silver-haired man watching a woman come into view.

He sucked in a breath.  He knew he shouldn’t be doing this, but he couldn’t help it.  No matter how much he tried, he could never and would never forget Rose Tyler.  The only woman who ever captured his hearts.

As though in agreement, he heard the TARDIS hum.  He rolled his eyes.

Rose stood on the street, observing the people as well.  She seemed sad in a way, and he struggled to remember why.  It had been so long for him.  His right side throbbed.

Maybe I can speak to her, just say “hello” and wish her well.  That wouldn’t be too invasive, would it?  Shouldn’t upset timelines too much.

He took a step towards her when he saw his leather-clad self appear and stand next to her.  The memory then came roaring back and at that moment, he knew he couldn’t do anything.  He stopped abruptly, clutching his side.

No.  I should not interfere.  I might screw up timelines so much that the past changes.  And I can’t have that.  Especially when it comes to Rose Tyler.

Rose and his ninth self engaged in conversation.  With his superior hearing, he heard her say “I want chips.”  He smiled.  He had never had chips since Bad Wolf Bay.  He had suggested it to Clara once when he had just earned this face.  But he was also struggling with realities and memories and so he forgot for a moment that it wasn’t the woman he loved standing in front of him.  Even though she reminded him of her, which is why he wanted to travel with her, she wasn’t Rose.  Never would be. 

Clara was her own person and the Doctor respected that.  He just had a moment of confusion from his regeneration. 

Twelve followed slowly behind the other two.  He didn’t want to arouse suspicion at all, just wanted another peek at the woman he loved so much.  They stopped in the chip shop, ordering some to go as well, and took their seat.  The two of them fell into easy conversation and Twelve could understand why he fell in love with her so easily.

She was his equal.

Sighing, he turned away and started his trek back to the TARDIS.  The pain in his right side continued but had settled into a dull ache.  For now.  He raised his left hand and rubbed his right side, just below the ribs.  He knew it would get worse the longer he let it go on.

Stepping into the TARDIS, he thought he heard the distant cry of “Doctor!”  He turned around but no one was there.  Shaking his head, he entered his police box and set the next destination.

Arriving a year later, he stepped out to a similar scene, though now in the evening.  The ache had spread to his left side and he knew there was not a lot of time left.  Still, he was determined to see her again.  He had to.

There she was, running down the street with his pinstriped-self.  The two of them were laughing as they looked behind them.  Twelve smiled.  Her laugh was always infectious. 

They stopped a little ways away from him, enough for him to get a good look at her.  He wanted her to be seared onto his hearts even more than she already was.  He wanted her to be the last face this face saw.

As though she sensed something, Rose suddenly turned in his direction.  He held his breath as she made eye contact.  The two of them stared at each other for what felt like a lifetime.  He grinned.  She smiled back and gave him her classic tongue-in-teeth grin that always made him weak in the knees. 

Does she know?

His brown-suited self turned to her then, breaking the moment.  She turned to him and they had a short conversation.  He remembered that too.  They were discussing taking a holiday after she visited her mother and got laundry done.  His younger self pulled a face at the mention of Jackie.  Rose playfully shoved him.

“Behave,” she told him with a smile.

Twelve chuckled to himself.  He always had been a bit afraid of Jackie Tyler.  The second human on Earth that could scare the daylights out of him, with the exception of Rose.  But that was for different reasons.

He suddenly let out a groan as a stab of pain hit him.  He could feel it.  The regeneration was going to happen soon.  He had to go.

Taking one last look at the only woman to have his hearts, he once again made eye contact.  And this time, they both held on.  It was as though Rose was somehow telling him “I know who you are.  The moment has come.  You are safe.  You are loved.”

Knowing Rose, she probably did say that in her own way.

Smiling, Twelve turned around and slowly made it back to the TARDIS, stumbling once or twice along the way.  He was aware of a presence lagging behind him.  As he reached the door, he turned around. 

Nothing. 

Shaking his head, thinking he imagined it, he stepped inside and shut the door.

Rose appeared on the side of the TARDIS, touching it tenderly.  She wondered which incarnation of the Doctor that silver-haired man was.  She was just about to go inside when she heard her counterpart call for her.  She left the blue box quickly, glancing at it as she returned to his Tenth side.

The Doctor hit the lever for the TARDIS to take off.  Regeneration was always better in orbit, flying through space while his body resets.  He sighed once more and looked at the monitor.

“There it is, silly old universe,” he said fondly.  “The more I save it, the more it needs saving.”

“Treadmill,” he added as an afterthought.

As he spoke to his future self, his encounter with his pink-and-yellow human was still fresh in his mind.  He had hoped that she would continue to be carried in his hearts.  He believed she would be.  Although each version of him grew away from her a bit, grew away from the pain, she never left.  She was always there, somehow whispering in his ear in quiet moments.  He still suspected that the Bad Wolf gave Clara to him.  That she really did see all of time and space and continued to protect him.

She promised him forever, after all.  And Rose Tyler keeps a promise.

The time had come.  He looked at the console of the TARDIS, his constant companion and dear friend.  His regeneration was seconds away.  Taking a final breath, he said…

“Doctor, I let you go.”

And he did.

Regeneration always hurt him.  But this time felt incredibly painful.  He didn’t realize why at first.  He felt his chest grow and his features soften.  His ring fell off his hand as it ended.  He took a few breaths to collect himself and looked in the monitor.

He was now a she.

A she who looked very much like Rose Tyler.  Blond hair, cinnamon eyes, and an accent.

“Oh brilliant,” she said with a smile.  Her Bad Wolf had done it again.  Had found a way to keep her with her again.  This time, for everyone to see.  Everyone to see what was locked in her hearts.

All because Rose Tyler kept her promise.

“How long are you going to stay with me?”

“Forever.”

And forever it may just be.