The Emperor needs Luke to turn to the dark side in order to live, because his fear of being overthrown fuels his connection to the force, and Luke's strength as a Jedi would destroy the Empire. Luke tells him that nothing will turn him, and Vader can still be turned back.
Ricocheted away from the Death Star and spun out of control, Vader was unable to stop Luke. The space station was destroyed, but Vader survived, and he flew into the far reaches of space. After the destruction of the Death Star, Darth Vader became obsessed with finding Luke Skywalker.
Luke was faced with the two most powerful people in the galaxy, Vader and Palpatine, and was tempted to finish the job. He was egged on by the way Palpatine threatened the Rebel Alliance's forces, and ever more so when Vader directly threatened Luke's twin sister Leia.
Palpatine. Palpatine was grooming Anakin for over a decade to become his newest Sith apprentice. Not only could Palpatine identify the uncertainty and darkness that resided within Anakin, but he actively used it to turn him toward the dark side.
Yoda. Yoda's knowledge of Luke Skywalker's true parentage was also confirmed in Return of the Jedi. As with Obi-Wan, Yoda believed that Anakin's fall to the dark side made him unsalvageable, with the Darth Vader persona being his only identity following his ascension to Sith Lordship.
Vader was hunting down the pilot who blew up the Death Star, and hired Boba Fett to find them. Boba was unable to, but he did give Vader a name: “Skywalker.” This, combined with his knowing Luke was Force-sensitive and had been trained by Obi-Wan, was what made him realize the truth.
Since Anakin's defeat on Mustafar, he needed frequent visits to his bacta tank to survive, and even the Vader suit itself was crude enough for Palpatine to control him. So with an aged body, a mind out of balance and the surprise of Luke's attack, Vader was caught at his weakest point.
During the battle, Anakin, who had been known as the Sith Lord Darth Vader, was redeemed by Luke and brought balance to the Force. However, the redemption cost Anakin his life, having been mortally wounded by the Emperor, Darth Sidious, while killing his former Master.
Vader's redemption in Return of the Jedi was not just about saving his son; it was also a defiance of the dark side's corruption and his own past as a Sith Lord. Vader's decision to block Luke from killing Palpatine was motivated by his knowledge that it would corrupt Luke and lead him down a similar path of suffering.
Vader was far more powerful than Luke and easily could have bested him. So, knowing that Vader wasn't allowed to kill Luke drastically changes the equation. His only goal was to make Luke mad, and he definitely accomplished that task.
He eventually became so desperate to find a way to prevent Padmé from dying that his fear was ultimately the main reason that led to his fall to the dark side. Vader screaming for the loss of Padmé. Even as a Sith Lord, Anakin still loved Padmé very much, but felt great guilt for his actions against her.
Summary. Darth Vader's failure to recognize Leia as his daughter in Star Wars: A New Hope stems from George Lucas's late decision to make Luke and Leia siblings. Leia's Force abilities and her lack of awareness of her true identity also contributed to Vader's inability to sense their familial connection.
R2-D2 was present when Padmé gave birth to Leia and Luke, so he knew Luke was Anakin's son – but what he didn't know was that Anakin became Darth Vader. In addition to that, Anakin's fall was surely a painful event in R2-D2's life, one that he definitely wouldn't like to remember or even talk about.
Summary. Anakin Skywalker's birth mystery is solved - his mother, Shmi Skywalker, reveals that there was no father and she can't explain what happened. Qui-Gon Jinn believed that the Force itself created Anakin in Shmi's womb, making him the Chosen One who would bring balance to the Force.
In canon, Vader found out because Luke told Boba Fett that he was “Luke Skywalker.” This was explained in the canon comic Star Wars (2015) 5. Vader only sensed Leia was Luke's sister because Luke was thinking about her on the Death Star II. When Vader tortu…
Kept secret was the fact that Leia was born to Anakin Skywalker, a Jedi who succumbed to the dark side and became Darth Vader. She was one of a set of twins, born in secrecy and protected from Vader and the Emperor.
During Yoda's encounter with Dooku, he opens himself up to the Dark Side for a moment. Through a realistic vision, he shows Dooku the unimaginable terror a Jedi Master as powerful as he would unleash should he turn to the Dark Side.
By bringing weapons into the Dagobah Cave, Luke already failed the test. Even Yoda explicitly said he will not need weapons. But like any young acolyte, Luke doesn't listen and takes his belt of weapons. He's focusing on the immediate threat (Darth Vader), and doesn't understand that being a Jedi is a journey.
Anakin Skywalker's attachment to his wife, Padmé Amidala, was the catalyst for his conversion to the dark side. Living beings tended to mistake attachment for love, whereas attachment was possession and as such, like everything of the dark side, had selfishness at its core.
