As discussed in the previous article Characters are one of the important elements in a story. Characters generally consist of a protagonist, his love interest and antagonist. Then there are some supporting characters. Any story whether in the anime or in any movie/series is a development of Protagonist as a different and upgraded version of himself in the end of the story. So the journey of this upgrade is the core of the story and it ends when the character is actually a changed one or upgraded one or decides to be the same. But here in the Anime, not only does the protagonist upgrade but also his Rival who once is the antagonist and later joins the forces of the protagonist.
One point to note is that a rival may be an antagonist but is not the Arch Nemesis of the protagonist but a supporting character who is next to the protagonist when it comes to the essence of the story. Rival is immediate competition to the main protagonist and the Rival himself thinks in that way. Whereas the Arch Nemesis is the greatest enemy to Protagonist. It's the main villain or antagonist in the story. In western world we know a lot of examples of Arch Nemesis like Joker to Batman. The relationships are totally different. In "Harry Potter" his arch nemesis is Voldemort. On the other hand, Rival is a kind of Anti-hero guy who hates the main protagonist because he always tries to compete with the main protagonist.
In Western writing we see the supporting characters who join the forces with the Protagonist to defeat the Villains. Many examples like DC's "Flash", "Supergirl" or "Arrow" are the shows where the Main Protagonists, Flash, Supergirl and Green Arrow have the team of their own who supports them to defeat the villains. Movies like "Harry Potter" where the main lead Harry Potter has always been backed by his friends Hermoine and Ron. Here in Animes the writers have gone a step ahead. In 3 out of 5 Animes you will find one character who is projected as a Villain and is actually the one, because all his characteristics are of the antagonist and he is projected as "RIVAL" of Main Antagonist. But later at one point the audience starts liking him, whether his looks or his characteristics/traits.
Why does it happen? Because the writer likes this RIVAL character and wants him to be involved in the further story and evolve accordingly. And this involvement of the character transforms him into Anti Hero from a pure Villain/Antagonist. There is a slight difference between an Anti Hero and a pure Villain/Antagonist. As a Villain/Antagonist is totally against the ideas of Protagonist and the world which the protagonist tries to support. Anti Hero just opposes the idea of being like the protagonist and being a kind hearted one. He is not against the system or the world but also does not follow all the principles in it. We can say that the Anti-hero is a protagonist from the start but it is realized later and he/she is not that kind hearted.
Now enough of a theory. Let's take an example of the legendary duo of Protagonist and his Rival, Goku and Vegeta from "Dragon Ball Z". Goku is introduced to the earth with a mission to destroy it but the injury changes him from Antagonist to Protagonist. If we look at his Character archetype, he is Helper. A person who is always worried about others and always ready to make extreme sacrifices but at the same type will show his rage to a villain when his friends and family are in danger. So Goku has a very kindhearted personality. Here Goku's Arch-Nemesis is Frieza, a Supervillain who is as strong as Goku and very opposite to what Goku is. Vegeta is Goku's Rival in the story. Believe me why I took this example because this anime and the duo are an inspiration to a lot of other anime and manga writers. Akira Toriyama has sincerely put a lot of effort into developing such a story.
So Goku is the main lead kind hearted Hero and on the other side his RIVAL is a Prince of Saiyans Vegeta, who is extremely arrogant, proud of himself and selfish in nature. So if you look closely, the traits of this duo are completely different from each other. But still at one point of time, when the world is in heavy trouble and no option left, they come together to support each other and save the world from the catastrophe. Here is where the Rival Antagonist transforms into an Anti-Hero personality. But in the case of Dragon Ball Z Akira Toriyama has beautifully written the character for Vegeta with a lot of twists and turns in it.
After defeating Frieza for some time Vegeta becomes a side character and then at the time of battle with Dr Gero and his androids he appears to be savior for two reasons. One is he achieves his Super Saiyan form with rigorous training on Moon and secondly Goku is affected due to heart disease. So this Anti Hero comes to be a savior for Earth when the main protagonist is in danger. Now what's next. Akira could have kept the character in the same role as a strong aid to the main lead but things change when we see the character taking the boots of Villain again after much of a time in Buu Saga where the wizard villain Babidi takes his control and turns him against Goku. Believe me this is the exact ohh my god moment!!! we used to have in childhood watching World Wrestling Entertainment (WWE) where a face (good wrestler) had a Heel turn (turning to Bad Wrestler). Still we thought it was Babidi who turned Vegeta into Goku but later Vegeta Admits that it's him who voluntarily took the power from Babidi to become Majin Vegeta so that he can just defeat Goku. Remember??? Yes, Rival is always the one to think of a Protagonist as his greatest competition and just waits for the right time to prove himself to the Protagonist. In this case as well Vegeta knew from the first that this was the right time to accept the power and challenge his immediate competition and the main Protagonist Goku. If you have watched the anime, then at one point Vegeta doesn't even hesitate to kill people so that Goku accepts his challenge. What a spectacular turn in the story.
I loved how Akira presented this. He teased their fight by making them opponents in the world tournament but the match never took place as Babidi had some other plans. So for a certain period we forget that part and suddenly it re-ignited when Vegeta accepts Babidi's power. Ohh My God, So nostalgic and amazing.