I have also thought of the Dark Side like a drug. Maybe not instantly addiciting as was mentioned above, but definately something that the user would crave and go through withdrawals if not used for a time. I always liked the term "seductive" in connection with the Dark Side. So, I was trying to find literary examples. I know some Shakespeare and was trying to think through the tradgedies but couldn't come up with any characters that I thought were a good analogy.
Then I tried to think of any of the mythologies I know and again was coming up a little blank.
In Plato's Republic, Socrates explains how a man goes from being a hero of the people to a tyrant. That was actually pretty interesting.
xhonzi