I had an idea for a book or a movie involving the multiverse, of course. The plot is centered around this dude who has an extremely rare brain mutation that allows him to interact subconsciously with past and present earths, as well "dark matter"-composed invisible universes which coincide in time with our own.
For example, he hears things on old radio commentary shows that coincide precisely with his current predicament, and the people in the past recordings can almost feel the dude's intrusion on their reality as he listens to the program, They comment on it by saying what the dude is thinking they're about to say, and it turns out that's the way the broadcast always was. (hope that makes some sense)
With the help of a new psychoactive drug which targets a previously unknown neurotransmitter system that allows the dude to become more aware of the existence of the multiverse, he learns that things that happened in the past are an unavoidable part of the future. There's all these other communicable universes within the multiverse that run parallel in time with him, and he builds a brain-computer module that allows him to interface with different, individual universes.
Basically, the message comes down to the idea that all things coexist at all times across the spectrum of the multiverse, which is composed of an infinite amount of universes, and that we are doomed to repeat the past as we inevitably cannot escape the relative non-evolution of human nature.