After the situation improved, Si Fan got someone to kidnap Mark and threatened Mary to work for him.
If Mary was the kind of heartless person who would betray without hesitation, Yin Xun could ignore Mary completely and resolve things the normal way. However, Mary trusted Yin Xun very much and handed the matter to her to resolve. Yin Xun would definitely help her.
She could not let Si Fan realize that something was wrong. Everything had to go according to Si Fan's plan for now.
In other aspects, Yin Xun was not worried about what Si Fan would do. However, Mark was in Si Fan's hands. This was a human life at stake. Si Fan was not someone who would abide by the law. If he was really anxious, he would readily kill someone.
In the original novel, Si Fan killed Yin Mo's family and even imprisoned and tortured her. Due to the effect of the protagonist's halo, Si Fan could bypass the law.
