maybe esme's apartment lease ended at the beginning of the year and that's when she moved in with leila? they could have met originally at the gym she works at (or something else entirely if that doesn't work!) and when it was mentioned that she was apartment hunting because her landlord was a terror, leila offered? esme will be the annoying roommate up at 5am and knocking on her door like OKAY it's time for a quick five mile run!