in the Dark Horse comic series star Wars Tales, which is now part of legends, it's revealed that Darth Vader did recognize C.3PO on Cloud City. when 3PO was shot by Stormtroopers, his parts were brought before Vader. because the Imperials thought he could hold valuable.
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.
Vader himself saves Threepio from destruction in the final pages of Marvel's Star Wars, before the series gets a relaunch taking place after Empire Strikes Back.
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.
In this version of events, R2's deux ex backup goes deeper into C-3PO's storage banks and reawakens his entire memory from the initial switch-on by a young Anakin in The Phantom Menace.
She senses Anakin when she reaches out to the pilot — and Vader realizes that Ahsoka, his former Padawan, lives on. In Season 2, Episode 18, “Shroud of Darkness,” Ahsoka's guilt manifests as a vision of Anakin, who's angry with her for leaving him all those years ago.
Since Bail Organa had C-3PO's memory wiped previously in order to prevent him from spilling the secret of Leia's parentage, it could be that this was a semi-regular occurrence for the droid given he couldn't be trusted to keep quiet about things.
Since Obi-Wan and Anakin often fought together, Obi-Wan was friends with R2-D2 as well. This means that although R2-D2 might not have immediately recognized Obi-Wan on Tatooine due to his age, Obi-Wan should have recognized the droid.
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.
Instead, the diminutive droid appears to have kept his own counsel, perhaps wary of interfering too much in Luke's personal journey. C-3PO lost those memories, but he remained with Han and Leia's family after Return of the Jedi, so can reasonably be assumed to have learned the truth by eavesdropping.
The lack of recognition could have come from an old man simply not remembering the passing droids of his youth. Lastly, Owen didn't seem the sentimental type to form any emotional attachments to droids. Being a practical man, he viewed them as tools to be used and replaced when they no longer functioned.
One of the mysteries from the original trilogy that was fueled by the prequels is why R2-D2 never told Luke that Darth Vader was his father, as he actually knew Anakin Skywalker and witnessed his turn to the dark side.
secondly, in Legends, R2 was given programming that actually restricted him. from sharing any information with Luke or Leia. about their parents or relation to one another. this was all part of the plan. to conceal this information from the twins.
The sequence calls back to a similar scene in Revenge of the Sith, when Bail Organa orders Threepio's memory be erased to prevent him from sharing information about Anakin Skywalker's fall to the dark side.
Bail's final line of the film and instruction to the Captain, says “…have the Protocol droid's mind wiped.” Because Bail Organa had them wipe his memory at the end of Revenge Of The Sith and he never came back to Tatooine until A New Hope.
Towards the end of the war, Anakin turned to the dark side and Padme died so her friend, Bail Organa took the droid as well as R2 when he took her daughter, Leia. C-3PO has his memory wiped unlike R2-D2.
Moreover, C3PO had his memory wiped at the end of Episode III. Thus he would not have remembered anything about Darth Vader or who he ever once was. There would be no memory connection by C3PO to his “maker” Anakin Skywalker either.
C-3PO accidentally became part of the Battle of Geonosis when his head was affixed on top of a battle droid's body after a mishap in the Geonosian droid factory. R2-D2 and C-3PO witnessed the secret wedding between Anakin Skywalker and Padmé Amidala on Naboo.
As a young boy, Anakin Skywalker constructed C-3PO to assist his mother, Shmi, on their home planet of Tatooine. When Qui-Gon Jinn, Obi-Wan Kenobi, and Padmé Amidala encountered Anakin while stranded on the planet, C-3PO met R2-D2, an astromech droid owned by Padmé.
Summary. A disturbing theory suggests that Darth Vader kept one of Ahsoka Tano's lightsabers for a darker reason, potentially using its kyber crystal to improve his own blade.
Thrawn learned that Anakin Skywalker and Darth Vader were the same person during a mission with Vader, but kept the secret to himself. Thrawn's knowledge of Anakin's history explains his surprised reaction to hearing his name in Ahsoka episode 7 and likely gives him an advantage against Ahsoka Tano.
Vader did not hunt for Yoda in any cinematic depiction. He and Sidious could not find Yoda as he had exiled himself on the planet Dagobah which had strong dark side energy that masked Yoda's presence in the Force.
