Yes, I think he’s stealing hearts. I created another post about it. I think he is stealing them from Regina’s vault and possibly stealing them from people as well and burying them to keep them away from Regina so that she can’t control people with them or kill people. Since people can appearantly live without a heart (Graham), it only seems to be a problem if Regina has control of their heart or destroys it. So I think he is stealing hearts in order to protect people and take power away from Regina.