With the roles that Felix takes, a majority of its ends up with him being the mastermind of all the evil deeds that occurs in the series.
Then again there are a handful in which he plays the minor roles, i.e. DIF IV (Jessica's father), Files of Justice, Triumph in the Skies, in which he has very little involvement with the storyline or plot.
The one thing that holds true in almost all the recent series is that he always plays the 'father-figure' role in the series.