Executive producer Dave Erickson has talked about what challenges the characters in Fear the Walking Dead will face in the back half of season 3:
There will be nobody in the immediate first few episodes, but we will meet a character down the road who represents a greater danger and evil than anybody we’ve met to this point. And it’s someone who I think Jeremiah Otto will pale in comparison to him. So there’s the potential of a Big Bad that will come to the fore later on. As the family comes together, and it will be somewhat traumatic and somewhat violent if they do come together, they need to be in opposition to something. So one of the things we’ll thread into the story as we get towards the end is who that force is, who that person is.
Source: Syfy Wire