I do sympathize with the Joker as his backstory,(featured in "The Killing Joke" ) depicts him as an ordinary chemical engineer who then became a failed stand-up comedian with a pregnant wife. He was desperate to support his family thus, he decided to take part in a robbery, leading his partners into the chemical plant where he worked. Later, he tried to back-out of the robbery but to no avail. The gang was caught by security and all were shot dead except the "Joker"."Joker" was confronted by Batman. Petrified, he jumped into a chemical basin. Upon seeing the "transformation" of his face, he was driven insane, thus Joker was born.
It was not really his fault that he became Joker. He had no choice. Therefore, I sympathize with the Joker.
------------------------------------------------------------------------------------------------
From this lesson, I have learnt that the personality of the characters are actually very important in a story. Heroes may bear good intentions but it may not show in their actions and Villains may not always be all that evil but sometimes forced by certain circumstances to behave badly.