Stein is your Meister, after Spirit became deaths weapon, it left Stein weaponless, until you came a long, death thought it would be great for you to be his weapon. You had your doubts about him after hearing what Stein supposedly did to Spirit.

After talking to him and getting to know each other better you tested if your soul wavelengths are compatible and they are. Then you moved in with him to the patchworks lab.

Stein wanted to strengthen your wavelength by insulting you. Now here you are sitting on the couch legs crossed and staring at each other.

"Your flat."He said bluntly