... another intelligent form of life existed?

What if another intelligent form of life existed?
Human beings are obsessed by the possibility that life exists in other planets.
Countless movies, books, TV shows are born from this fear-hope, and there are whole sub-culture strongly convinced that not only ancient civilization exist, but that they have already visited our planet.
So what if another advanced specie existed?

Maybe initially we would know if they are friendly or not. If they are friendly probably it would be a mutual knowledge exchange and could start a pacific coexistence with them.
But if they wouldn’t be friendly we would probably be involved in a battle for supremacy, and if no one won, we would have to live separated and split our planet’s resources, and the two groups would just ignore each other.
Our concept of alien life is firmly rooted on the belief that they look similar to the the Earth population. Almost all the main alien races in the realm of science fiction and fantasy are humanoids, but the basis of life as we know it may not be at all the fundamental rules of the universe. It may also be that even if they were sitting at the bar next to us, we would have not recognized them.
So watch out and keep your eyes open.