I have been always intrigued by the forms of evil. Every time you think of evil, what thoughts come in your mind - Satan, A mythological enemy of an incarnation of God, a Murderer, a rapist, a thief, a pervert, a mean person, a selfish person, a relative, an acquaintance, a historical figure etc? I am not saying these are not evil, they are for some, and it is a perspective. However, each personification says something about you. What you consider evil? What are you limits?A thief considers a murder as a bigger evil. It is very perspective.Anytime we do something unethical we try to give evil the blame by saying it took us over, that it got a control over us. What a pack of lies. It is just passing on the blame to a higher power very much like faith in God; you put your faith in evil. If you do something unethical and try to ask God to resolve the situation for you, I am sorry you are praying to a wolf in sheep's clothing. You are praying to a God but you are powering the evil. I am not trying to give this a religious or spiritual twist. Please stop kidding yourself, good and bad deeds live inside you.  It is desperate to say that you lost control on yourself or you made a call when given a choice. Something or someone lead to that choice but it was not evilness that gave you the choice. It was just a situation just like choosing a meal but with much more at stake. If you try to find a reason instead of facing consequences, yes you are a bit pathetic. But don't feel bad, it is all right. It happens to everybody once in his or her life. As a student I got a high once being mean, being a rebel, I felt that nobody could harm me, I can be a cocky arse and nothing could touch me. It was fresh, it was liberating. I felt so relieved after so long , the small burdens I was carrying on my shoulders lightened. Suddenly, I was happy, a lot happy. I had a few close friends who liked me in whatever I did. Many of them just smiled and accepted my cocky behavior and joined in . I was uncaring, I was untouchable, I would do something totally unlike me and feel exhilarated , excited. I truly believed this is the way the world survives; everything else is just a fluff. It went on, things in my life went from good to great. I was enjoying not caring about something I used to think a lot about. A few friends would try to put a forced smile when I was just a little extra mean and that little scorn hidden between their smiles will do two things - turn me against them little by little and make me feel even surer of myself and my true calling. There were a few people in front of whom I was still a bit shy of this avatar of mine, I tried to sugar-coat my exploits as harmless banters. They laughed, I felt better inside thinking I don't care what they do. I never for a second felt bad for what I did. The phase lasted really long. To date I still don't know how or when i got out of it. I recall it as a faded memory, probably because I ponder on it a lot. Most people forget that phase in their life. Some people do things that stick with them the whole life. I thank whatever the impetus was that got me out of that phase. I now know why I was feeling invincible, I was bathing in dung if someone threw some mud at me with an angry face . Their angrily thrown mud was nothing compared to stench of the dung I was bathing in. I just thought they are powerless or jealous. I never realized how powerless I was. I came out of it without knowing. After passing that phase, I had even more fun, I was laughing , eating with loved ones. I was falling in love, crying and running all over the place. I was again feeling strong, and the word is strong not powerful. I again became happy. 
Being evil or being mean is banal, it never gives you any reward it just changes your perspective and you start looking at how good your life has become. Some may find it dramatic considering mean and evil in the same tone. I am not saying you are a Satan if you are mean. I am just saying evil is not a big thing , it is small , it is weak , it is just as tiny a power as being mean is. You make yourself believe that it has given you wings. Don't fool yourself honey, you are just gliding with a towel between your armpits. 
A funny but true quote :If you really want to be a rebel, read your Bible, because no one is doing thatThat’s rebellionThat’s the only rebellion left.
Without any religious tone, if you want to be a happy person. Smile, do something good, accept yourself, accept your deeds. Sometimes your deeds are not mean, the way you handle them is.  
Do read about the Banality of Evil : I can't write about the article because it is like a non-stop brain food for me. I can discuss it for hours (ask my friend Joy). It will show you how the evil is not powerful we are .