Going into ""The Pickett Line," I wasn't sure whether or not Cochise should be trusted... let along assisted in the completion of the Volm machine. The construction was kept a secret and, even more worrisome, it's purpose and potential were unknown.
As annoying as Mariana has been, she went behind Tom's back and investigated the Volm device for a noble reason. She was and is concerned for the well-being of the Charleston residents and the entire United States. However, her methods and fundamental desire for order and control undermines her ability to lead.