So in Mothership Zeta add on we are formally introduced to Zetan aliens, before this there were alien encounters here and there but they were mostly Easter eggs and their canon status was dubious. So we get abducted, we escape, and we capture the Mothership, but the motivation behind the original kidnapping is left largely unanswered, you can ask Elliott but he is mainly just guessing based on no particular evidence. Let me start this with some things that almost certainly are not Zetan motivations: 1. they are not trying to conquer Earth. Reason for this is that after the nuclear exchange it would be incredibly easy for Zetans to swoop down, mop up what is left of the humans and take the place over, there were not that many humans left, those that were were concentrated in few key spots and almost completely defenseless, and even more technologically advanced factions would be easy pickings for Zetan Death ray. On a side note Zetans also did not cause the war, reason for this is simple, had they wanted to wipe out humanity they would not need the bombs, Zetan Death ray has been calculated to have yield of roughly 200 megatons, even if they wanted to be conservative with their resources a couple low powered shots to each side would be enough for both sides to instantly go nuclear on each other, Zetans did not need lauch codes as the bugged recording would suggest. 2. They are not harvesting us for food. Although their cryoexperiments may seem like effort to preserve food fresh there is no reason to freeze humans alive, dead human frozen is just as good food source as living, and that is assuming we are even edible for them. 3. They don´t want to enslave us as work force. Apart from Zetans having fully capable robot drones which would likely be way more effective and consume less resources they also seem wholly uninterested in developing means of communication, which would be vital for any slave labor force, after all even a slave needs orders, slave is entirely useless if you can´t tell it what to do. 4. They are not using us as guinea pigs to improve their own quality of life, in real life we use mammals as guinea pigs instead of bugs or fish because quality of data is directly proportional to how similar the select lifeform is to us, for a species in outer space who´s evolution happened completely separately from ours any data they may gather will be completely useless in affecting their own lives since they are so radically different. Ok, let´s talk about the things Zetans showed interest in: 1. They showed great deal of interest in cryogenics, for some reason they dedicated vast resources to trying to cryogenically preserve live humans. 2. They showed interest in human culture, they were around for hundreds of years and abducted people from wide range of historical eras, and they also forced this humans to recite their life story into audio recorders, this shows they are interested not only in human biology, but also in human intelligence. 3. They showed interest in reshaping human bodies, in particular hybridization with their own DNA, this experiments can be reasonably said to have failed since resulting abominations were feral and berserk. 4. They showed interest in human maturation, seen in case of Sally and her sister, as Zetans intentionally kept Sally a child where her sister was allowed to grow up naturally so that they can oserve the changes in real time. 5. They showed interest in human technology but at best only a passing interest, as more of a curiosity, they stacked vast amounts of it in the cargo hold but they do not seem to give it too much attention beyond that. 6. They showed interest in human biology as evidenced by vast quantities of human organs and blood samples on the ship. So on to the conclusion. Elliott theorizes that Zetans may have been the ones who seeded life on Earth in the first place, and their efforts in cryogenics certainly suggest they plan to transplant human life somewhere else. For what purpose they intend to do this is anyone´s guess, maybe they are trying to create a race of supersoldiers (after all your small band was able to run right trough the mothership). Or they simply want to preserve human race for their own purposes. Maybe in their own version of moral code survival of human species takes precedence over any individual human being, so they do not see performing horrific experiments on individual humans objectionable so far as it serves the survival of the whole species. Their interest in human culture suggests they plan to preserve human civilization it more or less its current form, perhaps the war disrupted their experiments and they seek to restart them somewhere else, by transplanting humans to another, more hospitable world. What are your thoughts on this?