Some people do invest very heavily in their characters, of course, and there is a feeling of hurt when the character is -- from the writer's pov -- misunderstood or misrepresented. (I did not appreciate some of the comments on Gracielis and Mary Sue. Because, you know, I so do not want his life and I so resent people thinking they can see into my head). This can happen in readers/viewers, too -- I have encountered fanfic writers who have a huge sense of ownership of a canon character and can be very unreasonable about it. And, as you note, people do seem to be much ruder on the web than in real life, doubtless because it feels less personal. I
In a better world, we would all treat each other as real breathing people who can be hurt and not just lash out in fear. In this case, I'm glad to say there is a fair amount of the latter going on, which is great. (Applauds tamaranth and katelliott.