Standard disclaimers etc...
"Impossible." Rose whispered as she stared up at the large blue police box that stood in the middle of Victoria Embankment. She tried not to remember the last time she'd seen a police box in that spot, so long ago and so very far away. She tried to ignore the rush of memories – a confident Northern accent, a run at full speed across Westminster Bridge, a hand that fit with hers just so.
Futilely telling herself the blue box wasn't real, but hoping with a painful, throbbing desperation that it was, she placed a trembling hand against the old wood. She pulled her hand back in shock when she felt the steady vibration she knew so well.
"Impossible." She said again as she pressed both hands against the door, this time keeping them there for a moment, savouring the familiar texture. When she leaned forward and touched her head to the wood she could hear the faint vestiges of a comforting song, old as Time itself. Exhaling the emotions that swept through her – hope, she thought, and maybe even a bit of fear – she stepped back, reached into her shirt and removed the chain that held her most valued possession. It took her three tries to get the key into the lock. When it finally slid in, she turned it, pushed open the door, and took a step inside.
With wide eyes she took in the ship – her home – and the man standing at the console. In the blink of an eye, not about to waste a single precious moment, the Doctor had crossed over to her and gently cupped her face in his hands.
"Rose Tyler, I love you." He said, leaning in to place a soft kiss on her lips.
"Impossible," she whispered a third time when they reluctantly pulled apart, half choking on the word as tears began to fall.
"Doubtful," he whispered back, grinning like he'd just been given the greatest gift in the world. "Improbable. Highly unlikely. But never, ever impossible."