Anakin succumbs to the dark side in "Star Wars: Episode III — Revenge of the Sith" due to his love for Padmé. Chancellor Palpatine, who turns out to be the Sith Lord known as Darth Sidious (aka the Emperor), manipulates Anakin into becoming his new apprentice and helping him execute Order 66 by promising that he'll teach him the dark side of the Force so that he can save Padmé. Sadly, he's unable to change the future, and Padmé dies after giving birth to their twins, Luke and Leia. The film explains why Anakin and Obi-Wan have a fallout as well as the tragic events that lead to Anakin becoming Vader, making it the perfect setup for any Star Wars movie or TV series post-Order 66.
