Never wrote for this fandom before, but I recently saw Season 1 and 2 (plus anything else that had to do with Rose) and I felt like taking a stab at the worst and best day in the life of my favorite dyed blond companion.
Disclaimer: Oh heck, I don't own any of this. Just playing around with Rose and the Doctor.
When the Doctor had sprung into being, fully formed and naked as the day, it was a moment of fury, of disorientation, and of a supreme urgency to take care of saving the day with his usual panache. Everything up to the point of the hand being cut off was clear as if it had happened yesterday, but there was a foggy sense of more and he sorted through memories to pick and choose what had brought this him to the TARDIS after the events of that fateful Christmas.
The feral thrill of annihilating the daleks was followed by a backlash of sorrow and self-hate. He had done his duty, he had gotten revenge for the death of his people, and he was keeping the universe safe. The other him, emotionally weak, hadn't seen the opportunity and the rightness of the prophecy. The daleks' own prophet had pled for death at the end so what difference who pressed the button. Those soft years of saving lives with Rose, with Martha, and then again with Donna were like a gauzy film whereas that last battle with the daleks on the satellite was fresh in his cellular memory. The other him forgot so quickly, it seemed.
And that included Rose emerging like a vengeful goddess to do the first time what should have been enough to leave them safe. The echo of her voice, the raw power leaking from her human shell as she had turned the emperor-god of the daleks to dust, he had been so proud and so whole. For a while, even if she didn't remember it now, she had been more powerful than a Time Lord and he had had a true companion. If he had been fond of her before, willing to cross worlds to save her, he loved her then.
In Norway, on a beach with an ill fated name, he watched the scene unfold between Rose and the Time Lord version of himself that he understood so well intellectually even if he didn't agree with his methods. He knew the other Doctor was making a case for Rose to stay here, with him, and he knew well enough to stay silent and watch himself manipulate her into doing as he thought best.
All the Time Lord Doctor needed to say were three little words, and he wanted to so very much, but she would never stay if she heard it from him. The Time Lord looked to the half-human and silently they agreed. The words had to be said, and they had to come from the one who could grow old and die with her. The conspiracy was made all the sweeter by her immediate and very physical reaction which jolted every new nerve in his freshly-generated body.
Somewhere, on a parallel Earth, he wondered if another him was regretting the decision.
Scratch that, somewhere on a parallel Earth he knew another him was full of regret. But the Doctor moved on with life, he found new distractions and locked away the bad times so deeply even he couldn't remember them sometimes. The gauzy memories told him Rose had a lot to do with forgetting those bad times.
In doing what was best for Rose they had made both her and her original Doctor miserable, but if the Doctor knew anything he knew Rose Tyler couldn't stay away from him. Impatient even at the best of times, 900 years notwithstanding, he only hoped he wouldn't scare her off before she was ready to see him for what he really was: mortal, half-Time Lord, and very much in love with her.
He squeezed her hand, excited about what this world had in store for him.