Emperor Palpatine, also known as Darth Sidious, is the feared master of the merciless Darth Vader and a follower of the Dark Side of the Force, being a Sith Master. Much hate rages inside him, which only makes him stronger, even more than the Jedi.
Note:The only fiction the Star Warriors have yet received has sadly been limited to back of package blurbs.
Palpatine rebuilt Darth Vader's body and twisted his mind to the ways of the Sith. As part of this process, the Emperor somehow used the Force to transform into an Imperial Shuttle to transport Darth Vader to the Outer Rim.
Later, as a sinister Lord of the Sith, Darth Vader was on a mission to crush the Rebels and bring young Luke Skywalker before the Emperor.