If you are planning on running an Evil aligned character in a Good aligned game you might face a few problems.
Generally it is a bad idea to make a character that goes against what everyone else is doing. It can be disruptive and cause a lot of inter-party conflict.
That being said, talk to your group to see if they would be fine with your idea before doing anything. If they are willing to play as a Good party with an Evil tag-along then that is up to them.
