Ellies Parents
So bear with me as I haven't actually played the game but saw Markiplier play it then looked up a bunch of stuff. So as most people know Ellies mom was a firefly who died of natural or unatural causes, which I personally think was an infection before birth. Mostly because she knew she would die. I think the immunity of Ellie comes not from her mother's infection before her birth but from her father. My theory is that in the Last of us Dlc Left behind, Ellie actually meets her father. Or rather his skeleton. I am fairly positive the skeleton of the army medic in the air duct was her father. Also this means he worked with ellies mom who might have been a double agent spying on the army for the firefly while being their army medic. Anyway I think he is Ellies father. Why? Because he stated he was immune. In the recording he says he was immune and that he tried to tell another soldier but she attacked him and he killed her. Also he constantly refers to an Ellis. Which might be ellie if he didn't know she was a girl when she was born. This is my theory and I thought I'd share it with people. I don't know if anyone already figured it out or not and if you did sorry. I just know what I heard and read during markiplier play through and a wikia. Commenter if you agree or not. Please don't be rude. Just a fan who sadly doesn't have a Playstation cause I'm poor. Well. Comment and stuff. Thanks.