Why would Ada WORK for Simmons though...I mean...Ada only worked for people cause she had her OWN plans later on...If Ada really is a staright villain it's kind of cheap for her to be and underling to this Simmons fellow...She would be her OWN boss because that's how Ada roles...The solo, go your own way type...No...I don't think she's actually TRULY evil or a villain because if she was she would be taking orders from NO ONE...
To bad Ada always took orders from SOMEONE because she always worked for an organization and one that she is mostly loyal to is the one that she is taking orders from.
Edit: Didnt see this post when I was posting my reply, what Bruno said.