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.
To answer the original question, I'm pretty sure that R2 never knew that Anakin became Vader. He wasn't there when Anakin was named Vader, he didn't know what happened on Mustafar. All he knew is that Anakin told R2 to stay with the ship, and that was the last time R2 saw Anakin.
R2 was on Mustafar when Anakin became Vader. That, perhaps, explains that he doesn't try to reacquire him. Why don't R2D2 and C-3PO ever alert Luke Skywalker of who his father really is? The two droids knew very well Darth Vader was Anakin Skywalker.
Why did R2-D2 never tell Luke Skywalker that Darth Vader was Anakin Skywalker?
Because R2-D2 did not know. The last time R2 saw Anakin was when he accompanied Padme and Obi-Wan to Mustafar; while Anakin and Obi-Wan fought, R2 and C-3PO loaded Padme onto the ship, then saw Obi-Wan return alone, upset, and holding Anakin's lightsaber.
What happened to R2-D2 after Anakin became Darth Vader?
After Skywalker turned to the dark side of the Force, the droid served Senator Bail Organa for a time in the Imperial Senate. Nineteen years following the purge of the Galactic Republic, R2-D2 played a pivotal role in helping the Rebel Alliance destroy the Empire's Death Star superweapon.
Why R2-D2 Never Told Luke that Darth Vader is Anakin - Star Wars Explained
Did Vader recognize C-3PO?
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.
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.
A 2017 Reddit theory posted by u/mybustersword adds to that by connecting to the notion of a "companion." It explains that Obi-Wan carefully praises Artoo rather than pretends not to know him, suggesting that he doesn't "own" R2-D2 in the manner that Luke is describing.
Darth Vader can not use force lighting, because of his severed arms. Robotic hands can't summon the force lighting. However Darth Vader can still use other forms of the force, such as force choke.
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.
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.
R2-D2 was part of the repair crew for the Naboo Royal Starship. He technically is owned by Naboo's elected royalty until Padme took him along for her senator duties. By the Clone Wars, Padme gave him to Anakin as she felt a droid like R2 was far more useful to aid Anakin.
C3PO had his memory erased so he doesn't remember at all. And I agree with the above statement about Obi-Wan and R2 having an off set agreement about there friendship. Also Obi-Wan and C3PO had plenty of meetings in the first 3 movies.
The bond between The Chosen One and R2-D2 goes back to as far as the beginning of the prequel trilogy. They first met aboard Queen Amidala's starfighter during Star Wars: Episode I - The Phantom Menace. Anakin was still very young, so he grew up and became a Jedi with R2 at his side.
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.
Every time she speaks, he remembers Padmé. Fighting alongside Sabé reminds him of fighting alongside his wife. While that is certainly painful enough, it's also reminds Vader of the man he used to be, a past he had long ago attempted to kill and bury. However, the memory of Padmé via Sabé won't let his past stay there.
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.
He states this with the line "I don't want the Emperor's prize damaged, so we will test it on Captain Solo." I would now add that he doesn't want Chewbacca killed either. If Solo is killed, Chewie is bait for Skywalker.
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.
Why does R2 not recognize Yoda in Empire Strikes Back?
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.
In Star Wars: The Force Awakens, set approximately 30 years after Return of the Jedi, R2-D2 is revealed to be kept in storage at the Resistance base on the planet D'Qar, having put himself in a low-power mode after Luke Skywalker's disappearance.
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.
