Character Heroes and Villains are a challenge to say the least. A Hero is always the Main Character. A Villain is always a secondary Character who works off of the Hero. The Hero relates to the reader and expresses the message; the Villain creates the plot and drives it home. How good and bad you want your Hero and Villain to be is up to you. Remember that the more evil the Villain the more complex and possibly more exciting the conflict and plot will be. This will also make your Hero act accordingly to the Villain depending on how good he or she is.
Remember to work up a personality for your character as explained in (HOW DO I CREATE A GREAT CHARACTER FOR MY STORY?) In the archived area.
Always remember that the Hero and the Villain represents opposite points of views. Because of this, your Hero will face a time in your story that will test his or her moral judgement, principle values etc., When this happens it will be up to your character what he or she will decide. Your Hero will decide what view to go with, tried and true or another way depending on the personality you gave this character.. Don't make it so complicated but try to make it interesting for the reader to relate to. Sometimes our Heroes and Villains become so close to each other confusion can set in for the reader. It is important to separate you Hero from your Villain in every way possible. By doing this you can as an author create two separate full characters both functional for the story along with personal traits. This will allow the both characters to be fully enjoyed by the reader.