Science. Emma and I sort of...encouraged your mom to separate herself from the Evil Queen and crush her heart.

[ Wow, saying it out loud sounds like a terrible idea. ]

And she did but it didn't work. So now there's two of them but we've been keeping the Evil Queen at bay. Mostly. It's...she...cursed David and I so that only one of us can be awake at a time.

[ Snow says that last part so fast because wow, they never saw it coming. ]