Leia's Force abilities and her lack of awareness of her true identity also contributed to Vader's inability to sense their familial connection. Vader's denial of Anakin Skywalker's legacy and his fear of getting hurt again prevented him from realizing the truth about his children until later in the original trilogy.
Leia was not using the Force or was currently Force-sensitive during her confrontation with Vader. She began training as a Jedi years later. All these reasons prove my point: Vader didn't know Leia was his daughter, and felt no presence of the Force in her, as she was not currently strong with the Force.
Darth Vader didn't learn he had a daughter until Return of the Jedi, when he stood before Emperor Palpatine. The Emperor's power probed Luke's mind, attempting to goad him to fall to the dark side, and he discovered Leia's existence. "Sister," the Emperor taunted.
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…
As far as we know, he never did. Only 3 people knew Luke had a sister: Yoda, Obi-Wan, and (eventually) Luke. The only one who could have told him was Luke, in the few minutes between the time he turned back to the Light Side and the time he died. That didn't happen on screen so it's safe to assume it didn't happen.
Yes. In Truce at Bakura, Anakin's ghost appeared to Leia, begging for her forgiveness. She rejected him. Only by Tatooine Ghost did she start to come around to the father underneath the suit, just in time for her to finally have kids in the Thrawn Trilogy.
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.
Darth Vader acts like he doesn't even know C-3PO or R2D2. They were with him since he was a child. He did everything he could to forget his past. Also, his plating had been replaced many times, and protocol droids all look very similar.
And they forgave Anakin. The ideas of the smiling heavenly force ghost of Anakin next to Obi Wan watching over Luke or Kylo being portrayed as a finally good person before his death obviously did not bother the writers.
She was not genetic Organa but still, she is rightful Organa. So yes, Palpatine knew that Leia is daughter of Anakin as well as the fact that Ben is the son of Leia and Han.
No, Anakin was never made aware that he had children until he is initially confronted with Luke, and then suspects between ANH and ESB that Luke is his son. Obi-Wan comments that "the Emporer knew, as I did, that if Anakin were to have any offspring they would be a threat to him.
The real reason why Obi-Wan Kenobi, the Lars family, or Darth Vader didn't act in the original Star Wars trilogy as though they knew C-3PO or R2-D2 previously is that the prequel trilogy, in which they first meet the two droids, had not been written yet.
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.
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.
Luke became famous after destroying the Death Star, putting him right in the crosshairs of the Empire. As The Empire Strikes Back picks up, Vader is obsessively searching for Luke, due to their familial connection.
Within Vader still resides a part of his former self, Anakin Skywalker, and it could be argued that this is why he can sense Luke while the Emperor cannot.
Luke and Leia never sensed that they were twins until Return of the Jedi despite both being sensitive to the Force. Anakin Skywalker's twin children are the original Star Wars trilogy's driving force, having been separated after Padme's death.
He didn't recognize him because again, they all look the same & it was decades until he saw him again. There was no reason to believe he or R2 even existed anymore.
