I know it's been 127 years since we last saw each other ...
Take it from there!
Why has it been 127 years? Was it supposed to be 100? Was it supposed to be 5?
Did their previous encounter(s) cause the long lives or is that normal for their species?
Was the last time they met right before a classic "Dear John" letter?
Does "John" need to be a man? Human? The same species? On the same time line? What if the writer or John is a self-aware machine?
Hmm, John is Sherlock Holmes's companion's name ....