About the character ( spoilers )
Erica is a federal agent doing counterterrorism. She deals with finding sleeper cells and basically eradicating them as much as possible. She's smart and intelligent and all the things that you would want someone who is protecting our country to be. I must have a hero complex. I keep gravitating toward these roles. She has a son, and she's in love with her son, and her son is in love with the Visitors. She has to deal with the fact that she has to save him for the most part. Her husband just left her, so she's a brokenhearted counterterrorist detective.
Protecting the son or the world? ( spoilers )
It's going to come down to both being the same thing. Her son is becoming a huge example of what is going wrong, of the fact that this is becoming insidious, that these people are like toxins seeping into our groundwater. They're going to be everywhere. It's a little bit terrifying. She's actively trying to do something about it, and it's like the smallest person you can imagine against an army of millions.