Revenge of the Sith, Anakin was tempted to the dark side by one of his most trusted mentors, Senator Palpatine, who offered to teach the troubled Jedi Knight a way to prevent the death of his wife, Pé. After intervening in Mace Windu's attempted assassination of Palpatine, Anakin pledged himself to the Sith, becoming Darth Vader. Palpatine later issued Order 66, which caused the Republic's clone troopers to betray their commanding Jedi generals and violently eliminate them all across the galaxy.
With only a few Star Wars characters who knew Anakin was Darth Vader, his identity was kept a huge secret. Anakin's turn to the dark side, however, led to much chaos and had several tremendous consequences. There were very few remaining survivors of the Jedi Order, the entire galaxy was in peril, and countless lives had been changed in a matter of minutes. Even Anakin's own body was left mutilated after his near-fatal duel with Obi-Wan Kenobi on Mustafar. But while Emperor Palpatine gained a new apprentice with whom he could rule the galaxy, Darth Vader actually lost a big part of his former self, Anakin Skywalker.
The Death Of The Younglings Represented The Death Of Anakin Skywalker
During Anakin's slaughtering of the Jedi younglings, audiences saw a brief shot of his anger-filled eyes. This was Anakin's first crime as the newly-appointed, Darth Vader, and an unforgivable one at that. The act of killing innocent children was completely against the code of the Jedi Order. It was also something the real Anakin would've never done as he trained a Padawan (Ahsoka Tano) himself and knew that the Jedi aspired to help the weak and make their lives better.
Darth Vader, however, constantly believed that the Jedi were wrong in how they interpreted the light side of the Force. Vader felt he'd be doing Sidious a favor to eliminate as many Jedi as possible even though the younglings were kids. If Anakin had tried to stop himself, it would've been impossible as Anakin Skywalker was no more at this point. His entire mental state had changed while showing no signs of remorse. He'd truly become Palpatine's evil Sith apprentice.
Obi-Wan Was Right To Believe Anakin Skywalker Was Dead
In Disney+'s Obi-Wan Kenobi, after slicing open Darth Vader's mask during an intense lightsaber duel, Ben finally saw the distorted face of his former apprentice. The two had a short conversation moments later and at one point, Vader said, "I am not your failure, Obi-Wan. You didn't kill Anakin Skywalker. I did ... the same way I will destroy you!" At that moment, Obi-Wan was right to believe his former apprentice was "truly dead" as Vader himself said that he killed off Anakin and any part of the latter that still existed within him.
There was no going back to the light side. Darth Vader's Anakin voice break cemented the transformation of a successful former Jedi Knight into a monstrous Sith Lord in Obi-Wan's mind. Kenobi finally understood his former apprentice's path in life as he'd given up by responding with, "Goodbye, Darth". Before that, Kenobi had always referred to him as Anakin as a way to persuade him back to being the good person he once was. However, he now realized there was nothing more he could do after hearing those words from the mouth of his former apprentice and was right to do so.
How Luke Skywalker Brought Anakin Back
Darth Vader's relationship with Luke was very different from that of his former master, Obi-Wan Kenobi, and former apprentice, Ahsoka. Luke only knew Vader as a father figure and never held a previous emotional attachment with him because he wasn't alive at the time. Vader chose to keep him alive after their duel on Cloud City, and it was this moment that caused Luke Skywalker to feel Darth Vader's good nature.
Luke reminded his father of his old name, Anakin Skywalker, and felt the conflict growing within Darth Vader while mentioning there was room for his redemption. In fact, Luke proved to be right in the end. In the final moments with his father, he was the only person that was able to unmask Star Wars' Darth Vader, which in turn freed him from the wrath of the dark side.
