You know, my first initial reaction was that Regina was going to end up being the Queen of Hearts, since, well, Regina does have a vault of hearts 😆 But I was thinking there’s no plausible way for Regina to be in two different realms unless she had a twin sister or something wacky like that or she knew how to travel between worlds and around what Jefferson told her. So I’m glad my first thought was proven wrong.
I’m all for the theory that Phee mentioned as well. Seems likely in my mind as to who the Queen of Hearts is. I think I’ll be rather disappointed if that theory proves incorrect.