I just finished a very entertaining story called A Week is just Seven days, isn't it? http://www.fanfiction.net/s/7873722/1/A_Week_is_Just_Seven_Days_Isnt_It Mycroft asks John to go to Afganistan to investigate some irregularities, and Sherlock doesn't really cope. It was very funny and has Sherlock reacting to John going somewhere he can't protect him.

It probably isn't what you are looking for as there is not an inkling of angst, but it is highly entertaining, so save it for a day where you need to be cheered up a bit.