Ppl need to realized Dewey is not controlling Sansui. Sansui is allowing her to order him around. He could literally turn around killed almost everyone in an instance. And he's probably only taking care of Rain because of his master's orders, not because he actually has compassion.
Also, this chapter reminds me of a scene in X-men: First Class.
Charles: Eric, they're just following orders.
Eric: I have been at the mercy of men just following orders.