3. Rule Of Two
LucasBooksThe Rule of Two was an Expanded Universe concept that was created on the premise that the Sith ranks had grown too large, diluting the power of the dark side. Because Sith crave absolute power, they were constantly battling amongst themselves for control rather then focusing their efforts on their sworn enemy The Jedi Order and Republic. With their numbers dwindling, a new tactic to survive was needed. It was decided there was to only ever be two Sith. No more, no less; a master and an apprentice. One would embody the full power of the dark side, while the other would crave to possess it. The apprentice would learn all they could from the master before eventually striking him or her down, claiming the title for their own. In turn, they would begin training a new apprentice in the hopes that one day they would be challenged for ultimate supremacy of the dark side. Despite the fact that much of the history surrounding the Rule of Two has originated from the Expanded Universe, its certainly feasible that either Darth Vader or Emperor Palpatine could have broken the rule and had a secret apprentice stashed away somewhere. Having this ancient fear be the Sith apprentice of either Darth Vader or Emperor Palpatine would be an excellent way to bridge the gap between the original trilogy and the new sequel trilogy. In fact, a proper film reintroduction to the rule of two and a much smaller scale enemy in terms of their numbers could just be what the Star Wars doctor ordered.