Charlie is a third generation FBI Agent. That is where her similarities to her father and grandfather begin, and end.
She began a field agent, but after her team was ambushed and killed by what Charlie had only been able to describe as 'monsters', she was placed on a deep cover team tapped for the sole purpose of watching, documenting, and in some cases bringing in these creatures who defied all sense of science, logic, or truth.
She's always known that monsters were real, and now she was going to attempt to protect people from them.
And, in some cases, vice-versa.