I just remembered that Anko has a cursed seal too. If I'm not wrong Anko and Sasuke both have the heaven seal and Kimimaru had the earth seal. Those seals were used to give more power to the respective user, but also was Orochimaru's mark for his special containers. We didn't see much from Anko, but I wonder if she is able to use the phase two of the cursed seal. Far as we know orochimaru just give those seals to special containers, Kimimaru was his favorite container since he had the perfect body (in orochimaru's words). From Sasuke he wanted the Sharingan and from anko...? What could Anko have that could be of interest for Orochimaru?