It had been sixteen years since Bad Wolf Bay, sixteen years since the last time Rose breathed in the moist smell of that horrid beach and where she had lost and subsequently gained the love of her life. It had been sixteen years since that small coral piece of the TARDIS had been given to her and his twin. It had been sixteen years, but you would never know.
The only change you could see in her was her darkened hair, which she let fall back to its natural color, and perhaps, if you looked close, you could see the age in her eyes, because the age on skin certainly did not show. They had talked about it, the Doctor and Rose. At first they were afraid to, at first there had been things they wouldn’t— couldn’t — talk about. At first Rose wouldn’t talk about the original Doctor and the Doctor wouldn’t talk about how he knew, beyond all doubt, the fate of Donna Noble, the most important woman in the universe.
And they wouldn’t talk about how neither of them seemed to age.
But that soon changed. With time (but only a little), the Doctor and Rose returned to their old lives. They grew the TARDIS. They watched the stars, visited planets, and met strange new people. And they were happy.
Soon, they came to acknowledge their indescribable feat of staying young. They had discovered that some pint of the Bad Wolf still which lived in Rose just as the half Time Lord that lived in the Doctor had ceased their aging, or at least slowed it remarkably. For Rose it was hard to watch Jackie, Pete, and Tony grow older while she never looked a day over 24.
But in sixteen years they had learned to take what was given them; they learned to accept it and feel blessed.
So, now, on some distant planet across the galaxy a million light years away, you may see an odd, but loving pair, holding hands tightly. Some days you may see them running. Others you may see them strolling through a market place, trying bizarre foods and talking to more bizarre people. But most likely, you’ll see them smiling and laughing, traversing the universe in a strange blue box. And you would never know sixteen years had gone by, because it was no different than twenty years ago, when they first saw each other in that little shop, and fell in love.
All you will really know if you should pass them by, all you will ever need to know, is that it is Rose Tyler with the Doctor in the TARDIS. And you will surely feel a spark somewhere within you telling you that that is exactly how it should be.