After C-3PO and R2-D2 landed on Tatooine, Jawas picked up the two droids, fitting them with restraining bolts. The Jawas sold the robots to Owen and Beru Lars and their nephew Luke Skywalker, a seemingly minor event that would change the fate of trillions in the galaxy.
Shortly after the Clone Wars, C-3PO's memory was erased, though R2-D2's memory was not. C-3PO and R2-D2 were assigned to the Alderaan cruiser Tantive IV, where they served senator Bail Organa for nineteen years, assisting in his fledgling resistance movement against the Galactic Empire.
Meanwhile, R2-D2's cameo in Obi-Wan Kenobi comes a bit later on at the 38:45 mark of the episode. He's briefly shown on the right side of the screen as Bail and Breha Organa talk about Leia. The appearances of R2-D2 and C-3PO in Obi-Wan Kenobi work perfectly within the established Star Wars canon.
Pawn Stars: Stars Wars Miniature Metal Lego C3PO and R2D2 worth $500,000
Why doesn t Darth Vader recognize R2-D2 and C-3PO?
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.
Obi-wan responds to starwars.wikia.com/wiki/Luke_Skywalker saying R2 belongs to him with, “I don't seem to remember ever owning a droid,” which is technically true, because Obi-Wan never did “own” R2 or C-3PO. Obi-Wan then makes a comment that suggests he's more than aware of R2's impressive capabilities.
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.
Darth Vader's true identity as Anakin Skywalker was a highly guarded secret, known only to a select few individuals including Palpatine, Obi-Wan Kenobi, Luke, Han, Leia, R2-D2, C-3PO, Master Yoda, Bail Organa, Ahsoka Tano, Darth Maul, Grand Moff Tarkin, Grand Admiral Thrawn, Jocasta Nu, Ferren Barr, Verla, Reva, ...
In The Phantom Menace, set 32 years before A New Hope, R2-D2 is portrayed as belonging to the Naboo defense forces, one of three astromech droids deployed for repair duty onboard Queen Padmé Amidala's (Natalie Portman) starship as it attempts to get past the Trade Federation blockade.
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.
However, the same could not be said for R2-D2, who never had his memories erased. While there isn't a canonical reason for this decision, the likely explanation may have been that Threepio was more likely to say something he shouldn't have.
He was also evasive with Luke as far as his relationship with Luke's father. C3PO was clearly created from some sort of kit or existing prototype since every protocol droid aside from coloring looks the same. He didn't recognize him because again, they all look the same & it was decades until he saw him again.
Return of the Jedi establishes that Yoda was aware that Anakin Skywalker had fallen to the dark side and become Darth Vader. When questioned by Luke Skywalker, he confided that Anakin was Darth Vader. Later, Obi-Wan Kenobi's Force ghost confirmed that Anakin had indeed fallen to the dark side and become Darth Vader.
According to Imperial Estimates in Star Wars Inside #87, only about 100 of the Jedi survived Order 66. Most were subsequently hunted down and killed in the years following the Great Jedi Purge.
Starting with Star Wars: Episode I - The Phantom Menace, Obi-Wan and R2-D2 helped free Naboo from the Trade Federation's invasion. Later, both served in the Clone Wars with R2-D2 assigned to Jedi Knight Anakin Skywalker. Since Obi-Wan and Anakin often fought together, Obi-Wan was friends with R2-D2 as well.
Three months after the Battle of Endor, Skywalker used the lightsaber during a mission to an Imperial research base on the planet Vetine in order to retrieve the last remaining fragment of a Force-sensitive tree. Skywalker gave his lightsaber to R2-D2 for hiding as they entered the Imperial base.
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.
Either way, while Vader can use most other Force abilities, Force Lightning needs to be channeled, and Vader's limbs are explicitly not connected to the Force. The Star Wars: Episode III - Revenge of the Sith Visual Dictionary confirms Darth Vader cannot use Force Lightning, and even suggests this is the reason why.
