During the zombie attack at the mansion and the group are locked upstairs in the attic, Christie starts to talk about forgetting cities/towns and moving out into the countryside.
My prediction is clementine found Omid and Christie and a boat or some kind of transport, and took clementine to the countryside, but didn't make it alive. The shadows are unknown yet but i think they are strangers.
I don't see how they could be Omid and Christie, because how did she somehow get from a middle of a city to the middle of a countryside when Christie mentions going there if they escape?
It makes more sense this way, tell me what you think.