In any case, 7 episodes into season 2 we finally learn who the aliens are, where they came from and how they got here. We still don't know for sure what they really want or why they decided to wipe out all humans on earth, except 2 but I suspect that's coming either next week or next season if there is one. It turns out the aliens a really are humans from the future coming back with a grudge to settle. I cannot imagine what we humans did that was so bad we needed to be exterminated, but I am going to make a wild guess. The father of these humans was a psychopath. His father had muscular dystrophy, and he passed it on within the race of aliens. The father being a nut job believes this genetic flaw is the result of something the 21st century humans did to him, rather than his own genetic fate. He instilled in his offspring a psychotic hatred for mankind and after generations, his descendants became brainwashed with this hatred. Does this make sense? No. But none of it makes sense. If the two humans from the 21st century are the "Adam and Eve" of this race of aliens, imagine the inbreeding! Maybe this is why one alien character had 3 miscarriages. The bigger problem is of course the time travel paradox. If the two 21st century humans were the originators of the alien races then how did they get on a alien space ship in the 21st century if they had not created this new race yet? All the contradictions could fill a book.
All of this was pretty predictable since the beginning when the "Adam and Eve" had visions of being with each other, including a vision of the "Eve" being pregnant. All we are waiting for now is the aliens to realize the truth and to seek a solution with the remaining human survivors. Or maybe the aliens will jump in time again, kill the Adam character and prevent the genesis of a race of aliens with serious genetic flaws in the first place. If either sides choose to prevent the conception of the alien race then what happens to 21st century earth? If there was no alien race with a huge grudge, then they would not attack earth and kill 4 billion people. Does everything go back to the way it was before the invasion? I guess we will find out.