Let's write!

Take a character - either original or a fandom character - and imagine them sometime in the future, when they're no longer doing the things they used to do, or perhaps living in a very different location (different town, country, planet). Ideas are a companion who's no longer traveling with the Doctor, or someone who has retired from their career, or even a character that was young and single in canon but now has a family of five, or is even a grandparent now.

Now, write a few paragraphs of that character encountering something that reminds them of 'now': the companion sees the Doctor (or an alien invasion!), the retiree has a chance meeting with an old co-worker, the grandparent goes to a college reunion.