Hidden Key (Attack on Titan and Shingeki no Kyojin Spoilers!!!)

It has been a couple years since the fall of Wall Maria, which was were Annie Leonhardt, Reiner Braun, and Bertolt Hoover entered the walls. But they weren't the only ones who entered, my name is London Goldsheath and I am not a titan shifter. But I am the half-sister to Annie and I am here to help with the mission of destroying humanity.