Based on alternate universe from that episode at the end of the fifth season, where M6 didn’t meet, and exact one horned jerk started a war with Equestria. I also have the unfinished fanfic based on this reality that I will write for sure someday, and the moment from which the art is depicted: having seen and went through the horrors of war, which she went to in order to quickly become the Wonderbolt, Rainbow Dash finally returns home and for the first time over the years meets with Fluttershy, who remained to work in the rear, and with whom they communicated only by letters. Finally, they can not keep the accumulated emotions from longing, the loss of friends, worries about close ponies and the fear of never seeing the most valuable of them again.