Regina couldn’t have Grahams heart, it was crushed to dust! If you truly believe she takes the actual hearts of people, then there’s no way she still has Graham’s.
That’s true. I had actually forgotten that it was destroyed during the killing. Then I can’t imagine it is anyone but Kathryn’s.
And really, that just makes sense is Regina is trying to frame Mary Margaret or if Mr. Gold is trying to force Emma to prove that it can’t be Mary Margaret and in the process start thinking there is more here than she believes now.