I've had a dream of a shapeshifter who's means of survival was to assimilate people, through which it would take on their appearance. It did this to avoid needing to show its true form. It had to do this constantly, like eating, because the disguise would wear off in a rather grotesque, contorting and needless to say, inhuman manner.
This is how it faced me. I could only see its grinning, twisted face in the dark, and then... well, it just walked into me. Suddenly, I was it, and it was I, and I had no longer control of my body. No pain, no violence, no gore, nothing. It just walked into and through me and blink, we're changed.
It was at this moment that I've come to know what it was like being part of a hivemind. It was nothing like western media portrays it at all. It wasn't the zombification of a person, a vessel to be driven from then on by a nihilistic taskmaster at the center of the hive. What it was, was an adjustment of personality that felt entirely natural. While your body is now a different one, your consciousness still exists the same as it has before, along with the consciousness of everyone else that was assimilated. Your priorities adjust accordingly, different body, different needs, and since you're no longer human, human morals no longer apply to you anymore, and you find yourself rooting for the driver of the organism because it not assimilating more people will mean your death as well now. In fact, the dream ended with me seeing the shapeshifter's next victim on a train and we couldn't wait to welcome her.
This entire sensation of being part of a bigger organism is utterly indescribable, it's not something a human in his waking life will ever experience. I felt known and understood as deeply as never before, and in turn I understood and knew the entire organism and its consciousnesses. Our personalities remained fully intact, everybody's individuality contributed to our collective survival ironically.
Being part of a hivemind sounds like a nightmare to most people, it's a more radical form of ego-loss, but as I was dreaming, it didn't feel scary at all. In fact, once I was assimilated, I felt better than never before. Still to this day I'm grateful to have had this dream because of the very unique things it made me feel.