One for the dark sides!:

Before Virgil left the dark sides, they had all learned something from each other. Virgil learned to hiss at people from Deceit, Deceit learned his sense of humor from Remus, and Remus learned how to do his eyeshadow/makeup from Virgil. This is how you can always tell the dark sides from the light sides because the dark sides have taught each other a lot of things in private that they Don't like to admit while the light sides teach each other stuff all the time.