How evil was Commodus?

How evil was Commodus? From my perspective and interpretation of the long passage I was given to read, I did not think that Commodus was actual a bad individual. I haven’t seen the actual movie of Gladiator but I have heard from sources that Commodus was portrayed as a bad individual; killing people, such as his sister just because he decided that he did not like her and so on. But on my defense of why I think he is not as bad as any of us, is because he was raised to behave in the manner of how he seems. As it says in the long passage of “Historia Augusta” that  “For even from his earliest years he was base and dishonourable, and cruel and lewd, defiled of mouth, moreover, and debauched.” I believe that in your young age a grown up must teach the individual what is right and wrong, and sadly for Commodus no one was there to teach him. And in result of this he is now remembered as this terrible villain in every “Gladiator” movie.