Poor Marie, completely unknown to her that her life is being used as a bargaining tool between a scummy sis-con and a really scary but equally cute heroine.
But damn, Val thought that through. If he betrays them again, Marie dies. If he kills Val, his deeds get released to Marie who will most likely be broken by the truth. If he attacks Val and fail, his deeds get released to Nord which will get Marie killed. From the get go, she left him no choice but to either comply with her demands or sacrifice Marie.