Vivi Delay

I am so confused about her character, too. At the beginning of the movie, she appears to be decent agent. I mean, she looks more like behind-the-desk type of an employee instead of field agent. But then after that, she turns into a bitch. Also, she was given the assignment to kill/arrest (can't know for sure) the Wolf (whom, for years, no one has identified yet) , which you might think, she must be a damn good agent. But then, she passes on the work to Ethan, who is a retiring agent WITH CANCER. Bottomline is: who is this girl? Or, is it really the intention to make her mysterious? idk.