The House in the Red Light District
[http://archiveofourown.org/works/962929] - - public:opalsong
Armin, Eren and Mikasa inherit a brothel. A very classy brothel, that's popular with the military. They have no idea what they're doing, but with Armin's cunning, Mikasa's ability to kick ass, and Eren's mysterious kink-discovering skills, they pull through okay. Mostly.