How did Vegeta unlock Super Saiyan?

[Totamo]

With all this debate about the form, it got me thinking: wasn't the whole reason Goku could do it because he was a purehearted warrior awoken by intense rage.

Vegeta is not pure of heart, not good or not evil, Freeza even said it, so explain this to me.

[Polyphase Avatron]

He concentrated his power into his shoulder blades, obviously...

[Darkprince410]

Vegeta is not pure of heart, not good or not evil, Freeza even said it, so explain this to me.

Vegeta would disagree with you.

Kuririn: “Th-that’s impossible…! Wh-why can he become a Super Saiyan…?! Don’t you have to have a tranquil heart to become one…!?”

Vegeta: “I was tranquil…Tranquil and pure…Pure evil, that is…I wished to get strong just by training earnestly…And so I went through stupendous training over and over again…Eventually, I realized my limits…Through my anger towards myself, I suddenly awakened…into a Super Saiyan!”

[Lord Beerus]

Vegeta is not pure of heart, not good or not evil, Freeza even said it, so explain this to me.

Vegeta would disagree with you.

Kuririn: “Th-that’s impossible…! Wh-why can he become a Super Saiyan…?! Don’t you have to have a tranquil heart to become one…!?”

Vegeta: “I was tranquil…Tranquil and pure…Pure evil, that is…I wished to get strong just by training earnestly…And so I went through stupendous training over and over again…Eventually, I realized my limits…Through my anger towards myself, I suddenly awakened…into a Super Saiyan!”

Good old, Vegeta. Abusing the loopholes in his Saiyan biology.

[DrakenballP]

He concentrated his power into his shoulder blades, obviously...

When I saw that scene I was so disappointed. That was just sad.

[Lord Beerus]

He concentrated his power into his shoulder blades, obviously...

When I saw that scene I was so disappointed. That was just sad.

That concentrated energy has to go somewhere...

[DrakenballP]

He concentrated his power into his shoulder blades, obviously...

When I saw that scene I was so disappointed. That was just sad.

That concentrated energy has to go somewhere...

Typically into your core, a place where excessive amounts of energy would normally be stored.

[Lord Beerus]

When I saw that scene I was so disappointed. That was just sad.

That concentrated energy has to go somewhere...

Typically into your core, a place where excessive amounts of energy would normally be stored.

And where would your core usually be?

[DrakenballP]

That concentrated energy has to go somewhere...

Typically into your core, a place where excessive amounts of energy would normally be stored.

And where would your core usually be?

Usually depicted in the center of your chest or stomach.

[Lord Beerus]

Typically into your core, a place where excessive amounts of energy would normally be stored.

And where would your core usually be?

Usually depicted in the center of your chest or stomach.

You know, your core is also be depicted to be in your back and hips, too.

[Super_Divine_Genki]

After being introduced into the franchise, Vegeta had always carried with him an air of smug, arrogant, cocky, and elitist behavior traits. The beginnings of his "armor being cracked" was when he had experienced a character-altering event during/after his battle with the Earthlings. Then, after setting his sights on the dragon balls and goal to take down Freeza, he'd experienced even more of a humbling of his character at the hands of Zarbon and Recoome -- but to a lesser extent. By the time he encountered final form Freeza, Vegeta felt that he was undoubtedly at the cusp of awakening the SSJ within him. He would then go on to be trounced and humiliated by Freeza in the worst way possible, before eventually being finished off by his former overlord and oppressor.

The seeds were all planted during the above chain of events. Plus Vegeta was already familiar with the legend of the SSJ -- he just needed to actually see it before his eyes as a confirmation and to really understand the magnitude of power that it could shoot him to.

To get back to the Freeza showdown, it appeared that Vegeta wasn't entirely wrong about his feeling that he was a SSJ. His power-up in the anime adaptation could be seen as him nearly getting there, but not quite, as his aura was noticeably imbued with trace amounts of the golden energies that would later go on to be the defining coloration of the complete SSJ transformation. So, my headcanon tells me that Vegeta had tapped into "the spark" at this point, but he simply wasn't able to maintain it due to not fully understanding what it was, plus still holding onto his arrogant traits (although at this point, the narrative was going with the pure of heart stuff).

So then, he's later resurrected and gets just enough exposure to Goku's SSJ power -- or new plateau -- to begin to form a more complete puzzle. Skip ahead to his adventures in space following the events of Namek, a return of Freeza, and witnessing yet another SSJ, and Vegeta had finally experienced 100% complete breakdown through repeated failings which hit him at his most vulnerable core when he finally turned his energy into hating himself. This required him to be stripped away of his -- as mentioned earlier -- smug, arrogant, cocky, and elitist traits which defined him, for that brief moment. And then it just clicked. [Cue an awesome flashback]

In summation, it was a series of events over time. If looked at in this way, Vegeta actually had one of the more satisfying SSJ moments of all. Whether someone really cares about Vegeta or not, the fact remains -- Vegeta's road to SSJ was very believable. When viewed outside of that moments context, a lot actually went into him getting there (and the show had to keep him up with Goku... and maybe, sell some toys while at it). Although, I wouldn't go as far to say that Vegeta becoming SSJ was written with all of those things in mind as the story was being told -- I know that wasn't the plan all along. It's a happy accident that his moment could be framed that way.

Vegeta's more exaggerated and perhaps idiotic behavior traits following that moment is another discussion.

That's my little half-shot in the air at explaining away an event that happened on an animated series which often times leaves it to the viewer to connect some dots, and not to be taken as a literal or factual be-all-end-all analyzation...

[DrakenballP]

And where would your core usually be?

Usually depicted in the center of your chest or stomach.

You know, your core is also be depicted to be in your back and hips, too.

Earth's core. Center.
Apple core. Center.
Human core. Center.

Thematic.

[swimtrunks]

The rage of always being in Goku's shadow aka Inadequacy.

[Lord Beerus]

Usually depicted in the center of your chest or stomach.

You know, your core is also be depicted to be in your back and hips, too.

Earth's core. Center.
Apple core. Center.
Human core. Center.

Thematic.

Flow of Chakra and psychic-energy, for which the concept of Ki is identical to. Not in the centre.