It's been a year or so after the final end of the Reapers, the Galaxy rebuilds itself. And Shepard? She's left the Alliance, and while she still has her Spectre status she's more or less retired. And the love of her life, Liara is off trying to put the Galaxy back together, which Shepard turned down and instead has just been hanging around. Though, recently she's started having visits from a certain Justicar that's been rethinking her life since the end of the Reapers War.