Explinations
If the doctor could have one moment with Rose Tyler before she goes into the parallel world, knowing he would never see her again, what would he say to her. This is my take on it assuming that he didn't go back in the last episode, maybe a missing scene where he potentially screws up the timeline by going back to see Rose, to explain everything to her before she's taken away.
"You know I love you right?" She asks looking up at him her eyes brimming with tears, not comprehending the severity of what had happened in "bad wolf".
"But you don't" he sighs, seriously. "You loved who I was, the doctor you knew and loved, he's gone now. There's me and, well, he is me but I'm not him. We're two different people, I know everything he knew and loved and feared but he still isn't me", seeing Rose's confusion he tries to simplify it. "Try this, every time I regenerate I become a different person, remembering every detail of my past life. The Doctor you knew is my past life"
"And I'm part of your past, your… you're letting me go?"
"No, not as long as you stay, but I cant love you like I know he did, see cause we are two different people and … "he breaks off
"He loved me? But all that time he wouldn't say anything"
"See here that's the hard thing, you say forever, meaning until you die and he says forever until you die but he will live on remembering everything, I regret remembering he didn't tell you before, you know, but I understand why he didn't, because as you grew old and got sick and died, he would stay young and healthy watching the woman he loved age and pass on knowing he couldn't."
Rose nodded her lip quivering, "I…. I understand"
"No you don't, you try to but it's beyond you, just do one thing for him and that is, when you leave me, don't waste your life pining for what has passed. Live for him rose, live the life you wanted to have with him, because I can't stay with you and he can't be with you and enjoy the adventure of living the normal life he never had, the little things, 2 in the morning waiting for a taxi." He grins and she smiles back. "Now give me a hug"
She complies and wonders if she could. The future didn't look so bright now that her Doctor had gone, but she makes her resolve. "I promise" she whispers into his brown coat. "I'll live for you….him" she chokes back a sob.
He grins at her again. "Now go and clean yourself up." she nods and does exactly that. The 10th doctor turns to the controls of the tardis and leaves bumping into himself as he walks out of the door. "Uhhh, Sorry, just had to get a message to Rose 'cause I know you wouldn't think of it until too late." He looks at himself "Well, you'd know you are from my future after all. God I'm an idiot for talking to myself. Now shoo before you screw with the timeline anymore." He yells after himself as he dissappers around the corner.
SO? What do you think? This is my first posted fanfiction so let me know. Constructive criticism is appreciated. Thanks