Evil has always been a fascination. Evil has dominated the media for as long as long as it has been around. Evil is much more exciting. Audiences are captivated by evil, a captivation unachievable by things that are good. Grendel is much more interesting than Beowulf for these same reasons. Grendel is an exciting, and mysterious character, and people are fascinated with things that they do not know or understand.
People are fascinated with evil, good is too predictable. People know what they are getting when they see something good. A movie about someone helping one hundred starving people wouldn't do nearly as well as a movie about someone shooting up a hundred innocent victims. Most of the people that enjoy these kind of movies would never do something like this in real life, thus the basis of it's appeal. Being nice and good is almost considered normal. If you help someone you aren't going to make the front page of the newspaper, but if you kill someone there's a good chance that you'll make the paper. People don't take great interest in every day things that they could do with out much of a problem or a resulting consequence. Good things just can't do what the evil things do.
Grendel is more interesting than Beowulf for the same reasons. Beowulf is like the stereotype hero. These heroes almost stay constant from story to story. The villains on the other hand are always different and always have exciting new characteristics. This is what keeps your interest. While Beowulf's character gets kind of boring and predictable, the villain, Grendel's character is un-predictable. It is never expected to do anything normal. A lot of times people will watch someone they hate just to see what he is going to do next.
If you don't completely understand someone or something then you are going to be more fascinated by it. If you completely understand something then you won't pa
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