Little Zombies or Little Aliens?

What would happen if humanity discovered extraterrestrial intelligence?

Better yet, what would happen if that extraterrestrial life was already here, but microscopic, malevolent, and in our heads?

This story explores this concept and could be the first chapter of many more. It could also branch off to feature a high school, Emo protagonist, who catches on, and tries to help humanity, giving him a sense of purpose he has long lacked.