2013, Andrew Niccol (Gattaca, In Time) -- download
Aliens invade, not only the planet but also the body. They are ethereal little silver fish that inhabit a body and control it, the human psyche slowly fading from existence, sort of like William Bell inhabiting Olivia Dunham in Fringe. But in some rare instances, and if we take the gist of the movie at face value, the human mind inside the body can be so desirous of surviving (say, in the case of being head over heels in puppy love) that the two live together. Melanie Stryder is that human and she lives in the head of Wanderer, the alien now controlling her body. Wanderer is not a bad "person" per se, perhaps a little tired of "her" long life and questioning the moral validity of being a species that can only exist at the death of another. Loosely veiled comment on being a carnivore? Who knows, who cares -- not the point of the story. The point is that Melanie is so strongly connected to her lover (romantic love) and her brother (familial love) that she can survive to influence Wanderer to do the right thing.
That right thing, which flies in the face of common sense, is to get back to her BF and brother. Why? Not really sure, but it is the mind of a teenage girl. She knows other aliens are after her; Hell, Wanderer knows this implicitly. But both make it to the desert hideout of the last few surviving humans, a hapless bunch of young adults, and a few wise old people, playing the part of WB-style resistance fighters. But there is an entanglement -- Melanie's BF does not believe he can have her back and is upset at Wanderer. Meanwhile one of the boys has a crush on Wanderer, on the personality that inhabits a pretty human body that is Melanie. There is something in the story that lends credence to the triangle here, with the characters actually weighing their feelings vs the reality of the situation. But is faint and gets lost in the silent glances. I just wish the alien invasion story had been better laid out, that there was more to it than a Red Dawn style resistance against a force that has pretty much already won. In the end, I cared very little about either.