The volcano stuff came from Mark Hamill:
"At the time STAR WARS was being filmed, I had no idea Darth Vader was my father," Hamill recalls. "I don't think Alec Guinness did, either, because in the scene where I ask him who my father was, he hesitated. Don't know how George made him do that. I didn't hear him saying, 'Maybe you don't really want to tell him,'" Hamill says, marveling at Sir Alec's performance.
"But it's tricky. I remember very early on asking who my parents were and being told that my father and Obi-Wan met Vader on the edge of a volcano and they had a duel. My father and Darth Vader fell into the crater and my father was instantly killed. Vader crawled out horribly scarred, and at that point the Emperor landed and Obi-Wan ran into the forest, never to be seen again."
"Now I wonder if it's true? I mean, there are so many things. For example, remember the Clone Wars? They could have cloned my father.
http://www.stars.handshake.de/starlog.htm
well darth vader was not luke's father in Star Wars (Ep Iv):
http://secrethistoryofstarwars.com/birthoffatherskywalker.html
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http://www.theforce.net/swtc/injuries.html
The second draft of The Empire Strikes Back screenplay tells an alternative story, indicating that Vader fell into a nuclear reactor shaft rather than lava. In this case, his infirmities may have something to do with mutation, radiation sickness and extensive cancer.) The Emperor's supposed involvement is interesting, as is the implication that Vader escaped under his own strength.
http://boards.theforce.net/classic_trilogy/b10002/8708417/p13
The Notion of vader being Luke's father first appeared in the second draft [of ESB]. Vader became attached to the dark side while he was training to become a Jedi. He became a Jedi and killed most of the Jedi Knights; very few escaped. Ben fought Vader and pushed him down a nuclear reactor shaft. One of his arms was severed, and Ben believed he had killed Vader; in fact, Vader survived and became a mutant. - Annotated Screenplays
STAR WARS: The Annotated Screenplays
http://www.amazon.com/Star-Wars-Screenplays-Laurent-Bouzereau/dp/0345409817
Ben fought Vader and pushed him down a nuclear reactor shaft, One of his arms was severed. This is like what happens to luke in ESB. One of luke's arms was severed and he fall into shaft. think for a moment.....could what happen to Luke in ESB be mirroring what happen to vader in The second draft of The Empire Strikes Back screenplay. Could it be that at the time of making ESB the fall down the nuclear reactor shaft was the Origin of Darth Vader.
Here is artwork of the front of vader's face from ESB: http://secrethistoryofstarwars.com/unmaskdrawing.jpg
Finally, the world was given a brief glimpse of the man underneat the helmet. "I shot this scene very carefully," director Irvin Kershner says. "When the captain comes in and Vader is sitting in his capsule with his back towards us, all you see are scars on the back of his neck for a second. I didn't want the audience to see anything else. I imagined that beneath the mask Vader was hideous; his mouth was cut away and he had one eye hanging low." http://www.secrethistoryofstarwars.com/visualdevelopmentofdarthvader.htm
Now the ROTJ Vader:
Return of the Jedi gave us some slight modifications as well, notably a further enhancement of the vocal flanging to make it seem more processed and electronic than in Empire Strikes Back, perhaps because the unmasking scene at the end would reveal a design that shows that Vader's natural voice is processed and amplified through an electronic system. The unmasking scene required more development be done on Vader. Since making Empire Strikes Back , Lucas had decided to turn Vader from a villain into a sympathetic character, unmasking and redeeming him in the final drafts. Because he was no longer a hideous monster, he was re-written as a "softer" and more human character--one early draft had him scarred and with a cloudy eye and a grey beard, but for the final version he was turned even more sympathetic, instead presenting him as a pale old man. This unmasking scene also necessitated a more elaborate design of the helmet. It is revealed to actually be three pieces,with the third piece being the actual mouthpiece which vocalises Vader's speech and processes his breathing. The cybernetic aspect is emphasized once again, with all sorts of vents, buttons and technological pieces decorating the helmet. Below is the prop used in this scene: Contrast that with the crude and simple two-piece mask used in Star Wars. Lucas also gave us insight into the extent of Vader's internal cybernetic re-construction--as Vader is being electrocuted, his skeleton is made visible, revealing his legs and arms to be fully or partially robotic, and his neck vertebrae to be artificial, perhaps explaining his respiration dependence as due to complete paralysis. Dr. Curtis Saxon has made an insightful commentary on this aspect. Below are screencaps provided by him which illustrate these things:
http://www.secrethistoryofstarwars.com/visualdevelopmentofdarthvader.htm
Now the rebooted Vader of Revenge of the Sith:
Finally, when it came time to making Revenge of the Sith, Lucas had to make specific choices regarding these elements that were previously only hinted at. Firstly, it was revealed that all of Anakin's limbs are artificial. Secondly, Anakin suffered no such paralysis in his "volcano" tumble, and in fact he is quite easily capable of breathing on his own, whether it is when he is clawing his way up the Mustafar slope or when it is in the medical chamber. It is strange that the film completely ignores this "iron lung" aspect, which was originally the very impetus of the whole cybernetic transformation.
In the film, a large gap exists between the scene where the medical droids begin work on him and the next time we see him, where he is more or less completed and already in the suit. Such a huge jump in time makes it seem as though Anakin has neither any respiratory needs, nor has any integral cybernetic enhancements to his organs or tissues, contrary to what Return of the Jedi implies. The emphasis is instead placed on his horrible imprisonment, reflecting the "tragic" view of Vader that the prequels show. We do, however, get a brief glimpse of the inside of the helmet, showing us high-tech HUD displays and a red-tinted electronic perspective (similar to Terminator). Lucas had to also make a decision on how to visually portray the Vader suit. Rather than making a choice with chronological consistency in mind, in other words going with the suit shown in Star Wars , Anakin was instead given the cyborg-emphasized design of the later two sequels. This design was given even more robotic overtones however--the hand-sculpted mask of the original films was remade using a robotic tool to ensure the mask was perfectly symmetrical. The chestbox was now made to be fully integrated into Vader's torso, creating a cyborg look. Finally, the helmet was made to connect underneath the breastplate, instead of overlapping on top as it did in the original films--this subtle but effective re-design gave Vader a more robotic look. Finally, Star Wars was altered where possible to match the depiction seen in the subsequent entries--James Earl Jones' voice was enhanced for the 2004 DVD release to sound more like the electronic version of Empire Strikes Back, Return of the Jedi and Revenge of the Sith .
http://www.secrethistoryofstarwars.com/visualdevelopmentofdarthvader.htm
Both the falling into fire and falling into a nuclear reactor seem to play into the Unmasked Vader, we see in EBS and ROTJ
Maybe George had not made up his mind on which one he wanted by the time the OOT was finish.
The OOT's Vader seem have both Origins.
If you like the falling into fire idea, then Anakin falls into fire (a volcano or a molten pit).
If you like the falling into a nuclear reactor idea, then Anakin falls into a nuclear reactor.
or if you like both, then it is both.
some-fans like Star Wars (Ep IV) and do not see vader as luke's father.
So, pick the one you like and research it.
For myself, I think the Vader falls into a volcano or a molten pit idea is a dumb idea because a person would just burn up on (or before) Impact.
more likely the some of the people who worked on ESB thought this too and GL changed it to the vader falls into a nuclear reactor and is radiated idea.
Now, GL has millions of Yes-men (like Rick McCallum) around him and the falls into a volcano or a molten pit idea returns for EP III.
I feel like most things in the PT, it is a really dumb idea.
Like The Visual Development of Darth Vader says:
he (vader) is quite easily capable of breathing on his own (in Ep III).
(EU BULL) The novelisation, however, states that Anakin's lungs were destroyed by breathing in the harmful super-heated gases.
one has to wonder why Obi Wan and Padme suffered no such side effects despite only slightly less extreme exposure.
And so on with the really dumb old George Lucas ideas.
Man I wish Lawrence Kasdan and Irvin Kershner work on the PT.
I'll take a mutant cyborg (cybernetic arms, legs, lungs, back and god only knows) vader in a iron-lung suit over the Burn Quadriplegia vader.