10 Crazy In-Universe Rules Star Wars Characters Must Follow
5. Sith Are Expected To Kill Their Masters
By their nature, Sith are untrustworthy and scheming individuals. Whenever the Sith Order was at the height of its power, it would constantly be undone from the inside, by a some power-hungry upstart who sort to claim ultimate supremacy. Due to this, the Rule of Two was created.
The Rule of Two was a doctrine set up hundreds of years before the events of the Phantom Menace. It allowed for only two Sith lords to ever be in existence at any one time. Once an apprentice become more powerful than their master they were required to betray and overthrow them. This ensured that the Sith became exponentially more powerful and ruthless with each iteration.
But it also put both the master and apprentice in something of an awkward situation. The nature of the relationship meant that if the master was a good teacher, it would inevitably lead to their pupil doing them in.
This practise went on for hundreds of years before Palpatine eventually attempted to put an end to it by employing the Rule of One.