(Written in the BBC Sherlock world sometime in Season 1 or 2 [pre-Mary and Rosie]; there aren't any spoilers if you haven't watched the show though) John is home when a thunderstorm begins. His PTSD kicks in, the thunder causing him to subconsciously revert back to his time in Afghanistan. Sherlock comes back and helps John through the episode. At the end is some cute friendship/fluff :) There is no explicit Johnlock in this story (much like the BBC version lol) so imagine them how you wish :)
4 parts