WARNING: spoilers below
Yeah. With the FBI guys they got more resources and, no, there wasn't any previous connection between Benicio and Emily's characters. She reminds him of his wife and/or daughter (innocent and unwitting in the face of insurmountable corruption and violence).
I love Brolin in this, btw. So annoyingly laid back.
While I don't think this is Villeneuve's best, I still think it's a fascinating film and one of the better 2015 outputs (which was a pretty great cinematic year).
There's much to be said about the theme of abuse that runs throughout, specially when it pertains to its female lead.