Falsely believing that the Dark Side is the only key to save Padmé's life, he submits himself to Palpatine's teachings-as a newly anointed Sith Lord, Skywalker has now completely fallen under the sway of the Dark Side.
Falsely believing that the Dark Side is the only key to save Padmé's life, Vader submits himself to Palpatine's teachings. As a newly anointed Sith Lord, Vader has now completely fallen under the sway of the Dark Side.