When he made his first appearance in Dragon Ball Z, Vegeta was a Saiyan underling in the Frieza Force, conquering planets and selling them to the highest bidder under orders from the group's titular tyrant. As an elite Saiyan Prince, there was nothing more humiliating to Vegeta than working for Frieza, the man who murdered his father and ruled over his race with an iron fist. When Vegeta finally arrived on Earth with his partner Nappa, they did major damage to the planet, resulting in the deaths of Yamcha, Chiaotzu, Tien and Piccolo. The villain even proved just how ruthless he was when he vaporized Nappa after his teammate lost to Goku.
However, since those early days, Vegeta has grown a ton as a character, giving him one of the best redemption arcs in all of anime.
The next time Vegeta appeared was on Planet Namek, where he killed innocent Namekians and Frieza's soldiers in pursuit of the world's Dragon Balls, with which he wanted to attain immortality. Vegeta was still inherently evil at this point, driven by an overwhelmingly strong desire to revenge the destruction of his homeworld and gain liberation from Frieza. However, this saga showed a more complex side of the proud Saiyan warrior -- a sign that Vegeta had the capacity for change -- when Frieza mortally wounded him.
In a teary-eyed emotional confession to Goku, Vegeta revealed it was Frieza who molded him into the ruthless and heartless warrior that he had become. Vegeta expressed sadness he'd been harboring heavily for his entire life, even going so far as to plead with Goku to not only avenge their eradicated race but also stop Frieza from creating more hateful and vengeful subordinates. This scene symbolized a change in Vegeta's character moving forward, pushing him more into the anti-hero role, as he cared more about his own strength but no longer wished to destroy the Earth or pursue the Dragon Balls for immortality. It was also the beginning of his maddening obsession with surpassing Goku.
After being wished back to life and to Earth by the Namekian Dragon Balls, Vegeta began his new life on Earth, moving in with Bulma at the Capsule Corporation and eventually conceiving Trunks. At first, Vegeta didn't recognize or entertain the idea of a relationship with Bulma, as his only goal was attaining absolute strength. He left Earth and went on a treacherous journey through the cosmos to find Goku and do battle with his eternal rival. While the Saiyan Prince did not locate Goku, he found something much more valuable than an exchange of fists: Vegeta became a Super Saiyan himself.
Having reached new heights of power, Vegeta became even more arrogant than before. However, the Saiyan Prince exhibited yet another change to his character, staking a claim on Goku's life that included rescuing his fellow Saiyan if he was he ever in any kind of life-threatening danger. Unfortunately, Vegeta's desire to preserve life didn't extend to anyone outside of Goku, as he showed little to no care when Dr. Gero attempted to kill Bulma and an infant Trunks. However, that changed with the "Cell Saga."
Meeting and working with Future Trunks helped Vegeta to care about the boy more, and the Saiyan Prince officially changed sides and became a Z-Fighter during the Cell Games when the villain murdered his son. Feeling as though his reckless and irrational decisions cost Gohan the opportunity to defeat Cell and save the Earth, Vegeta humbly apologized to Gohan. Later, he made good on his apology and helped damage Cell enough to give Gohan the opportunity to seize victory. If not for Vegeta's last-second attack, Cell would have run rampant across multiple galaxies and destroyed them all. It was here Vegeta finally accepted his life on Earth, developing an affection for Trunks and Bulma in the process. However, Goku's untimely death left him with an even greater obsession that even his newfound family could not cure.
The "Majin Buu Saga" was one of Vegeta's most disappointing moments in the franchise, as he allowed the dark wizard Babidi to control him to reignite his rivalry with Goku. Vegeta eventually came to his senses and sacrificed himself to defend Earth, hugging his young son beforehand in a heartfelt display of affection. Vegeta then later joined forces with Goku to fight against Super Buu and Kid Buu, setting aside their rivalry for the greater good of the Earth, risking his very existence in the process. By the end of this saga, Vegeta's transformation into a kind-hearted and caring character was finally complete -- a stark contrast to the cold and ruthless murderer he had once been.
10 years after the defeat of Kid Buu, Vegeta now has a great deal of love for Bulma, even skipping training completely as the two prepared to welcome their daughter Bulla into the world. This love even extended to young Trunks and his future counterpart, as Vegeta risked his life to save Future Trunk's timeline from Zamasu. The Saiyan also entrusted Goku with his promise to restore Universe 6 and shared valuable energy to his now friendly rival that was key in defeating Jiren.
Vegeta's redemption arc is not finished just yet, though, as he is currently training to defeat Moro so that he can avenge the Namekian people that the villain savagely murdered. Still, the once murderous and cold Saiyan Prince has become a loving husband and father willing to stake his life for the sake of his family and his home, making for one of the greatest redemption arcs across all of anime.
