If there's one part about Vegeta's arc that I absolutely love, it would be this:
His regression in season 8 was very well done. It wasn't shoehorned in and it made sense. I remember seeing on Reddit years ago people complaining about this specific part of his arc, saying that it made no sense for him to regress the way he did when he was redeemed at this point. But consider this. It makes perfect sense when you factor in one thing: he wasn't redeemed yet. He was still going through his redemption arc by this point.
Vegeta wasn't raised to be a family man. He was raised to be a killing machine. He was raised with the idea in mind that he would one day be the king of the Saiyan race. All of that got taken away from him. His belief that he was the strongest Saiyan alive was taken when Goku became a Super Saiyan and defeated Frieza, and again when Gohan became a Super Saiyan 2 and killed Perfect Cell. And then Goku makes the choice to stay dead instead of coming back to life via the dragon balls. So now, Vegeta's one rival, the person who he swore he would one day surpass and defeat is gone for good. So all Vegeta has left at this point is the family he created with Bulma. Something that he most likely never envisioned for himself. So he decides to live a life on earth with her and their son.
Everything seems to be going fine for Vegeta....until the World Martial Arts Tournament happens. And Goku decides to return on this one day so that he can participate. Suddenly, all of the feelings that Vegeta bottled up over the last 7 years since Goku's death comes rushing to the surface. Finally, after all this time, Vegeta could finally prove that he's better than Goku. They even get matched up to fight each other in the tournament! How lucky is that, right? And then this guy happens:
And just like that, Vegeta's chance to fight Goku is now shattered thanks to this new threat to Earth. Instead of his attention being on him, Goku has his sights set on defeating Buu before he can be revived. For the entire time Vegeta, Goku, Gohan, and the Supreme Kai are in Babidi's lair, Vegeta is angry. He's waited 7 years for the chance to fight Goku again, and now that he finally gets the chance to do so, this happens. We see Vegeta's mood get worse and worse throughout the time they fight Babidi's minions, and it's gets so bad to the point where Babidi is able to get Vegeta under his control. Now, as Vegeta pointed out later on, he actually could of fought off Babidi's mind control. But he chose not to. Why? Because he saw how powerful Babidi's minions were while they were under his control. So Vegeta figured he could use some of that power to do this:
Fight Goku without any interruptions. Which is what he wanted from the start. Even though he knew that fighting would give more energy to Buu and thus revive him, Vegeta didn't care. So long as he got to fight Goku. Keep in mind that this is the same guy who let Semi-Perfect Cell absorb Android 18, despite the fact that he knew it could end up being a bad decision. But Vegeta didn't care because he wanted a good fight.
Now there's one line that Vegeta said to Goku during this fight that always stuck with me from the moment I heard it back when I was a kid. When Goku asks him why did he do all of this, Vegeta responds with "Because I wanted him to reawaken the evil within my heart. I wanted him to return me to the way I was...BEFORE!!! I WAS THE PERFECT WARRIOR! COLD AND RUTHLESS! I LIVED BY MY STRENGTH ALONE! UNINHIBITED BY FOOLISH EMOTION!!! But slowly...over the years... I became one of you. My quest for greatness gradually giving way to this life of mediocrity. I awoke one day to find that I had settled down and formed a family. I had even grown quite fond of them. Would you believe, I almost started thinking that the Earth was a nice place to live. Do you understand now, Kakarrot? That's why I needed Babidi! To set me free! By releasing the evil within my heart! He has freed me of these petty attachments. And I have to say it feels pretty good."
That entire speech he gave to Goku summarized PERFECTLY the internal conflict that Vegeta had going on within him. On the one hand, he wants this. He wants to feel strong again. He wants to defeat Goku and prove that he's better than him once and for all. He wants the life of a warrior back, because for so long that's all he knew. But on the other hand, he knows that the way he's going about it is wrong. Like he just admitted to Goku, there's a small part of him that loves the life he made for himself, and that he loves his family, too. Which is why Goku then says to him "Do you really believe what you're saying?". Now, Vegeta doesn't respond to this, but he doesn't have to. His silence is his answer. After that, the long awaited fight between these two begins. And after a while, Vegeta does come to the realization that he fucked up big time, and that he needs to do something to make up for it. Which is why he does this:
He knocks Goku out while his back is turned. Why? Because he wants to fight Majin Buu alone. Because if it hadn't been for Vegeta's desire to fight Goku, Majin Buu probably wouldn't have gotten the energy he needed to be revived. So Vegeta decides to take full responsibility for everything and take on Buu himself. To me, this is when his redemption arc comes full circle, because of his sacrifice. He knows that he can't beat Majin Buu through normal means, so what does he do? Blow himself up in an explosion that he's certain will destroy Buu along with him.
Vegeta even says in his mind that he's doing this for Bulma, Trunks, and even Goku. Something that I'm pretty sure a lot of us never thought we would ever hear him say. That he's doing something for other people. That he's not doing this for himself. I'm pretty sure that he saw this as his way to atone (hence why this move is called "final atonement" in the video games) but the fact remains that he did it anyway. Sure, we see Vegeta get angry when Perfect Cell killed Future Trunks, but still. That moment can't compare to this one. All in all, Majin Vegeta is the best part of Vegeta's redemption arc and the way how it's written really did an excellent job in wrapping it up.
