Still they lived on
At first, it wasn't noticeable.
It was only after Lestrade's hair turned an unpleasant shade of grey, when streaks of white can be found in Mycroft's hair, when Mrs Hudson breathed her last breath. Then John noticed, he and Sherlock have barely aged.
It was after Lestrade was on his dying bed, when Mycroft resigned from the government and retired to his newly brought country house with Anthea, when even Molly's hair begun to turn white. Then John noticed, the crime-solving duo is still young and strong.
It was after Rosie entered middle age and hade her own child, when Mycroft's coffin was lowered to the ground, when Molly retired too. Then John noticed, he and Sherlock still looked to be middle-aged, not so much different from when he first got back from Afghanistan.
It was after even Molly, so young when he first met her, had choked out her last words, it was then John realised, he was going to live forever.
It was after Rosie's tombstone had been craved out, after his grandchildren became grandparents themselves, after all the villains they had dealt with had gone, after everyone they had ever known is dead.
Still the residents of 221B lived on.
The world changed around them, John doesn't use his old browning anymore, instead in its place is a high-tech laser gun. Even their flat isn't the same anymore as it was 200 years ago, when Molly, Lestrade, Mycroft, Mary and everyone else they cared about was still alive and breathing, it became lonely, just the two of them, sitting in a scruffy flat.
Still they lived on.
When the officials came to their door, asking them to board the last ships to Mars, them people realised who they were, the great Sherlock Holmes and his companion, John Watson. They moved to a flat on the red planet, named 221B, not very different from 221B Baker St.
Still they lived on.
Over centuries and centuries, when people have come and gone, John knew he doesn't feel grieve anymore, his feelings have long gone, buried with those he loved and cared for thousands of years ago. He could hardly remember them anymore, Mrs Hudson and Molly and all that, for once he envied Sherlock, but deep down he know he still grieves for them, secretly.
One day, Sherlock pulled out a photo album, inside was pictures and photos of their old life, solving crimes and having a laugh with their friends. They just looked at the photos together, smiling at the memories of them thousands of years ago.
John knows they will live on, forever. But had excepted the fact long ago, because at that moment, as he looked across the table at Rose, he realised that their old life had never really gone, it was just waiting for the right moment to come back.
So, my first Sherlock fanfic, it was hard writing this, as I teared up a bit towards the end, I had really expected for it to turn out to have so much feels, I had thought it would be a cute one with a bit of feels, but, ah, seems that it was leading me to it after all.