Sort of Dead space meets Star Trek with some bugish/plant parasite like aliens, they ate this tasty looking gloop (that could be made into human food) that started the trasnformation process and were not very hostile but were quite determined at conquering the human race.
There was a cute little girl that was mostly immune to the gloop who was trying to escape, outside the ship, which cinematically was cut away to a few times, was a cloud of human slaves all coccooned in changeling like sacs for feeding on heat and fluids, the humans were quite happy in there with some plant attached to the back of the head keeping them sedated and blissfully unaware of the situation.
The bugish/plantish creatures didn't really have any set goal or objective and were struggling to figure out what exactly to do, the humans in the cloud they had would be sufficent for at least a century and conquering more humans just would waste energy rather then be productive.
So there was a bit of an impasse and the aliens and humans just kinda started living together with the aliens pretending to be all menacing and the humans actually being scared of them, a little.
It worked until some human found the cute little girl and realised the aliens were't actually invading any more and things kinda settled down and they both got along quite well with the aliens trying to find a way to corrupt the little girl so they would one day be unstoppable, even if they didn't really know what to do with that unstoppableness.