The Red Legion is a chaotic evil guild. To play evil, whether in theater or a role-playing game, you must consider three basic flaws of humanity: fear, selfishness, and ignorance. Most evil can be attributed to these three traits. The Red Legion is a highly selfish system. Generally, a character completely determined to rule over everybody else, at the expense of anything but their own skin, will be drawn to a society like this one (just as perhaps some people in real life may be drawn to corrupt companies like Enron. Even in a fantasy world, it's the same concept).
Therefore, the Red Legion has very little comradery, because everybody is using one another only to advance their own ends, which ultimately will crush those beneath them. However, everybody must depend on one another until those selfish ends are achieved, in the most self-serving ways possible. Of course, very few could ever reach such a pinnacle of rule, so many understand that the highest level of power they could achieve for man years is to be part of a collective that provides an increase of personal gain. In this sense, teamwork and partnership does exist, but only on a superficial level, to boost the ends of those within that system, until they reach a high enough point that they can stab somebody in the back, or walk over the weak to rise to the next level.
The next anti-virtue is fear. Dictators use fear to control the minds of others and thus increase their own influence. Fear can command the weak of mind, and some may neglect their own sense of morality just to appease their master. In addition, fear of basic concepts of life; such as pain, insecurity, and even love, can lead to a philosophy of spitefulness and xenophobia, which can motivate a character to join a dark and menacing society as a means to get back at a certain people, in a futile attempt to justify themselves for their hatred. This can branch into worse traits, such as blood-lust and a desire to kill to gain pleasure and gratification.
Finally, there is ignorance. If you are playing an Orc, or a skeletal minion, most likely such a simple minded creature does not know better than to follow the strong. And certainly, an evil society will appear as strong and powerful on the outside (whereas philosophically they are weak). Therefore, an Orc might choose to follow such a path simply out of respect for the strong, while being ignorant toward everything else. In real life, it's a bit more complicated, but being without any form of awareness leads to destruction. A look at our planet today reflects this-- the way people waste, litter, and pollute, much of which is out of ignorance.
So, to sum it up, when playing in this guild you can think of evil sorcerers as selfish and power-hungry, desperate to rule above the rest because that is their only real meaning in life. Characters that are mindlessly violent, and full of rage, are likely motivated by some intense fear, and brutish characters who are primarily dumb servants are more likely to be of pure ignorance, they don't understand what it is they're doing or the chaos they're causing, and they wouldn't care if they did know.
The Religion of Agathala: Chaos
Tn all the mythos I've written, and the many stories that have played out on free form games over the years, I decided to create a division of two factions, the Order of Gogel, and Agathala's Legion. the Order represents a struggle between good and evil, a Chaotic / neutral alligned society, and the Legion is commanded by a representation of ultimate evil.
In this case, it is destruction. Agathala only wishes to undo creation, and waste away in the excess of it all during the process. He is the sentient force behind all the obstacles that we face in life. In other words, the Devil.
Followers of Agathala, true followers, desire chaos, to undo everything that is made in order to bring everything back down to their level, where they are in control. Somebody builds a house? Tear it down. Somebody falls in love? Kill them both. Somebody does a good deed? Reverse it.
Of course, creation is always a more powerful force than destruction, and therefore evil is always doomed to fail. However, in the process of combatting it, we learn to appreciate more strongly what we have, and we can preserve. Only in this sense is evil ever productive.
Agathala's Seductive Power
Agathala is also the master of physical pleasure. Just like a drug addict may shoot up at the expense of his or her own life, so Agathala taints the weak minded with similar effects. And, when making your character, this could also be a motivating force behind the evil tendencies. It takes great willpower to resist physical gratification as being the ultimate goal. And, for some cultists in the Red Legion, such resistance is pointless, and they will do anything they can to appease their dark masters and get their fix, even if it's ultimately destroying who they are and spreading destruction.
Agathala and his followers seem to have an ultimate goal of glee. Perhaps one virtue is they truly live in the moment, but all they want out of that moment is to destroy and fulfill their unholy amusement at the expense of everything else. They have no long-term plans, short of destroying all life in the universe until they are the ones on top, and then destroying each other until only one survives. Perhaps, only then, they will find their dark contentment. In the meantime, their hobbies are excess, excess, excess.
Some may allign themselves with these dark masters out of a desire to "simply have a good time" whereupon they will certainly find their good time, but it will be a pox on their soul that will ultimately damn them forever.