Several million years ago, or less, a large vessel holding aliens crashed near Earth. These aliens were not comparable to us – they travelled in space, but also drifted up and down dimensions, using natural tides to travel. Time means very little to them and they were in their Armada a universe onto themselves. But then, 3 million years, half a million years ago, they crashed and were left marooned here near Earth.
These aliens then started implementing a plan to build a new vehicle, and since these creatures were lazy, their trained local pets to do the hard work while they slept. To them the trained monkeys – humanity – are just biological robots. They enter us, redirect our actions, and leave us again.
But there aren’t enough of them to control everything. This is a problem. And there is another problem – some of them have become rather sentimental about the humans, and they have started feeling regret about what’s to come next.
When they leave they basicly abandon Earth as a died out husk. They will leave, continue on their voyage, and the Earth will be a used-up cinder. T hat’s their plan; but some of them have second thoughts.