Nailed it. As I was saying>>94180612
The comic hasn't ruled out the possibility that that could have been true at one point, that she came from the real world, but the situation seems to have shifted into that just being her backstory. My money is on this possibly being tied into what Strange did to make her fit into the 616 more fluidly.
But that moment, if it comes, will be pretty heavy, I think, that moment when she realizes that. It essentially solidifies that there's no way back for either of them.
Fuck, what if she never even really had a brother? What if he's a byproduct of her comic backstory? She didn't seem all that broken up over thinking she'd killed her fucking brother at the outset.