a traitor
Examples
I love treason but hate a traitor.
Whenever you hear a man prating about the Constitution, spot him as a traitor.
A society person who is enthusiastic about modern painting or Truman Capote is already half a traitor to his class. It is middle-class people who, quite mistakenly, imagine that a lively pursuit of the latest in reading and painting will advance their status in the world.
He who speaks to your face is not a traitor.
Give a traitor good words and you make him loyal.
The hasty man was never a traitor.