Real-world: they weren't connected when the original films were written. Same goes for how he didn't sense Leia's relation to him or Force abilities when standing directly in front of her.
Why doesn t Darth Vader recognize R2-D2 and C-3PO?
Perhaps, Darth Vader just figures that this is another protocol droid and not C-3PO. Obviously, C-3PO does not recognize Vader because his memory was wiped at the end of Revenge of the Sith.
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.
The base assumption of why Obi-Wan doesn't remember R2-D2 -- in light of the prequels -- is that Obi-Wan is feigning ignorance in A New Hope to downplay the importance of the droid's arrival.
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.
Why Didn't Darth Vader Remember C-3PO in The Empire Strikes Back? Star Wars Explained (Legends)
Why didn t R2-D2 tell Luke Vader was his father?
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.
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.
You saw how Luke's attitude completely changed when he realised that was actually Yoda and so did Yoda's behaviour. As for the r2 thing, is incredibly likely he just suspected R2 had had his memory wiped several times since they last saw each other.
Threepio was also there when Luke and Leia Amidala Skywalker were born. They were later left under the care of a Captain Antilles. In order to protect Luke and Leia from their father, Darth Vader, Bail had C-3PO's memory erased, causing Threepio to forget everything from his past life.
Vader mocked Luke for his lack of training in lightsaber combat, and he easily pulled the lightsaber out of Luke's grasp through the Force. However, before Vader could strike the unarmed Luke down, he suddenly recognized Luke's lightsaber as his own former weapon.
While Obi-Wan Kenobi seemed not to know R2-D2 in Star Wars: A New Hope, one theory argues that he recognized the droid but chose not to tell Luke. Despite acting as if he did not know the astromech droid, one theory holds that Obi-Wan Kenobi recognized R2-D2 in Star Wars: A New Hope.
Obi-Wan Kenobi has no idea who C-3PO is when they meet in “Star Wars: A New Hope” even though the prequel trilogy later told us that the two certainly knew each other.
Though it sounds like he thinks Anakin is dead, he could also be viewing it as Obi-Wan does, where he believes Anakin died when Darth Vader was created. There's a hint that Owen knows Anakin was Darth Vader by the time of A New Hope.
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.
Why is C-3PO forbidden to translate the Sith-Runic language? Rather simple. All protocol droids have the ability to translate. But a Senate ruling put in a rule that required all translating droids to be forbidden to translate, and if such system is overridden, to erase the droid's memory.
Darth Vader only learned he had a daughter in Return of the Jedi - but there's no evidence he realized she was Leia before his death and redemption. Darth Vader may have never known Princess Leia was his daughter in Star Wars and never cultivated a relationship with her, even when he was a Force ghost.
Shortly after the Galactic Empire was formed, Bail Organa had C-3PO's memory wiped clean in order for the droid to not spill any confidential information. When he purchased C-3PO and R2-D2, Owen Lars also wanted the droids' memories wiped after he learned they were looking for Obi-Wan Kenobi.
Did C-3PO lose his memory after Revenge of the Sith?
As a consequence of this process, C-3PO had to undergo a complete memory wipe, and he agreed to it. However, R2-D2 had a backup of his friend's memory, and by the end of the movie, C-3PO's memory had been restored.
He was still fairly new to the droid's mannerisms, slowly picking up on small phrases and sentences. After the original Star Wars, Luke understands R2-D2 better than ever, so much so that the Jedi Master has full-on conversations with the droid. By this point, there's no question that he's fluent in the language.
During the Clone Wars, it was common practice to wipe the minds of astromech droids after every mission to avoid the risk of Separatists taking valued information. But Anakin remained staunchly against this idea for R2-D2, meaning the droid never had to worry about losing the memories of his past.
However, while Yoda acts as though he had never met R2-D2 before, the Star Wars prequel trilogy, released decades later, revealed that Yoda was already well acquainted with the famous astromech droid.
Many of Jabba the Hutt's thugs were killed by Skywalker. Skywalker hid his lightsaber inside R2-D2's dome for the mission to rescue Captain Solo from Jabba the Hutt's palace.
Although Lucas portrayed R2-D2 as a defiant droid who refused to listen to his master's orders, the theory video claims R2-D2 wouldn't stay with the ship because the last time he did that, Anakin never came back.
Instead of being in the life suit, Vader looks like an older Anakin who never received the devastating injuries, and Padmé and Luke (who struck down Palpatine) are by his side. It's during these visions Palpatine realizes Luke - who he only knew as the Rebel who destroyed the Death Star - is Anakin's son.
