Bringing Ellie along is just a nuisance. But in the game, it is Tess who convinces Joel to take Ellie. Joel would have just gone back to the QZ had this request not been made. (Or Tess not died
Ellie's reaction to Joel's story is hard to read. When he first tells her his version of events she's lying in the backseat of his car, having just woken up. As he finishes the story she rolls
Logic predicts that Season 2 will pick up where The Last of Us Part II does, with Joel and Ellie living in Jackson in their own places. We'll likely get a little scene immediately after the events