those asking about what other forms of intelligence the dark seekers expressed...
Will Smith was losing his grip on reality, he was making mistakes. He misinterpreted the dark seeker willingly stepping into the light and causing himself pain as a degeneration of his basic survival skills due to lack of food supply, but really that was his mate that was captured and he did it out of compassion/hatred, which are two very human emotions. Besides the obvious copying of the trap and the dark seeker opening the roof so the others could get in, did you not see the main DS directing the movements of the others?
He was issuing commands, gesturing the DS to attack will smith in waves. Sending them in from different angles, 2 at a time, etc. Not only that, the dogs had leashes. This dark seeker DOMESTICATED these animals. That means he/they were capable of tying knots, pacifying and training animals (like humans do), and using them to their strengths.
People must have missed it, but to those wondering why only the dogs attacked Will Smith and not the DS themselves, there was an article hanging up in one of the houses on the wall that had a headline saying how canines were capable of walking outside in the twilight hours hours. I guess since they have more of an immunity (i.e., cant get infected by the airborne strain) they are less photosensitive to light. The sun was juuuust going down, vs the DS who only came out in the pitch black of night, so thats why only the dogs chased him down at that scene and not the DS. It was too early according to Will Smiths watch, that was first warning. At least, that was my understanding of the scene.
To go back to a previous point, there are several reasons why I believe Robert chose to kill himself. First being, as far as he was concerned, his life ended the moment his family was killed. You can see by him repeating his promise to his wife to the new woman, he's only hanging on to fulfill this promise and 'fix the problem.' He does this. He also must have realized that, like himself, he would do anything for his wife - just as he figured out that this DS would do the same. Think about it - to the head DS here, Robert just "killed" his girlfriend. (Though to Robert, he "saved" her - notice the difference). So the man was pissed. Robert must have realized that they'd never stop coming after him or his kind, and the woman and kid had no chance unless he didn't go with them. And without a purpose anymore, or a friend, how could he possibly go on alone anymore? He was trying to kill himself the night before at the pier, and now with his mission concluded, he just decided his purpose was over and he wanted to join his family. I guess when he saw the butterfly and remembered the words of his daughter, he just... I don't know, believed again or something. So it wasn't so much his death to dramatize the ending, but an actual, conscious choice of the character himself.
