He grabs her hand and pulls her around a corner. They struggle to catch their breath, leaning against the wall and each other for support. The brick feels cool under her fingers and his breath is warm against her neck.
It has been six years since they met. Six years since he took her hand and pulled her from the life she knew before. Six years, two universes, and three doctors (one a half-human-meta-crisis) later and here they are again, running for their lives down a city street from an unknown alien terror. It is as if not a day has passed. The quintessential Doctor and Rose.
Her breathing steadies and she looks up to see he is grinning at her with that smile-Oh, that smile! She knows in that moment that she will follow him anywhere, across the world, across a hundred worlds, to have that smile be for her. He leans his forehead against hers, still grinning. Some things never change.
"Marry me, Rose Tyler." And some things do.
His words are a declaration, not a question. For a moment the world stops and narrows to encompass only the Doctor and herself. In his eyes she sees stars, and moons, and life, and time.
But mostly she sees how much he loves her.
Then her hands are on his shoulders, on his face, and finally pushing through his hair as she crushes his mouth to hers in a breath-stealing kiss. When the kiss ends she knows her face and neck are flushed. His are too. He kisses her again.
"I want everyone to know that I'm yours." He says between kisses. "And you're mine." He nuzzles his nose against her throat. She runs her hands under his vest and across the soft material of his shirt. "I am going to spend the rest of my life with you and I want everyone to know."
They only break apart when a food cart explodes in a flash of green light a few hundred meters down the street. He still holds her hand tightly though. He quickly glances around the wall and then back at her, anticipation in his eyes.
"Well, what do you say?" he whispers.
She says the only thing that she can. With a smile to match his she pulls him along as she dashes out into the street. "Allons-y, Doctor!"
Not everything stays the same. Some things get better.