The Dragon Ball series is mostly known for its battle sequences, but one element that doesn't get a lot of recognition in the anime community is the redemption arcs. Most of Goku's biggest allies were originally his enemies, with Ten Shin Han, Piccolo, and Vegeta being some of the most prominent, although Android 18 is also a very good example.
Furthermore, it could be argued that Android 18 is one of the best examples in Dragon Ball when it comes to redemption arcs because she went from one of the biggest threats on Earth to a loving wife and mother. However, a lot of people would like to know what happened to 18 and why she had such notorious growth throughout the series.
Disclaimer: This article contains spoilers for the Dragon Ball series. Any opinion expressed here belongs to the author and not Sportskeeda.
Explaining when and how Android 18 became a good person in the Dragon Ball series
The truth is that Android 18 was never really evil in the main Dragon Ball timeline, and that is something that even Kami mentioned to Piccolo right before they merged into one being.
Kami mentions that Android 17 and 18 didn't do anything evil at the time. It's important to note that the majority of the evil they committed during the series took place in the timeline of Future Trunks, which has been stated to have Androids with some differences in power and personality.
However, this doesn't mean that Android 18 was never really on the Z Fighters' side, and things began to change when Krillin decided to spare her life by destroying the remote control that could have ended her. Furthermore, Krillin later wished for her to be human, starting a connection between the two of them, and eventually they got together, getting married and having a daughter.
It is also worth pointing out that the bulk of Android 18's character growth in the Dragon Ball series happened off-screen, between the events of the Cell and Buu sagas. However, she has been fairly consistent throughout the years ever since, being Krillin's biggest support and also being willing to fight when push comes to shove, with the Tournament of Power arc in Super being the most prominent example of the latter.
Android 17 and 18's redemption arcs
There is a strong argument to be made that Android 17 and 18 have two of the saddest and most tragic backstories in the entirety of the Dragon Ball mythos. They were changed and modified by Dr. Gero against their will just so they could fight Goku, a man who had anything to do with them, which is why perhaps they were not really evil in the main timeline of the series.
That is mostly shown and confirmed throughout the story, particularly after the Cell arc, when they are free to do what they want. Android 18 settled down with Krillin and their daughter. Meanwhile, Android 17 stayed on an island, focusing on protecting nature and living a very quiet life, with some fans theorizing that the impact of Android 16 was very significant in their lives.
Krillin's decision to spare Android 18 was probably the wrong one at the moment, but it also further emphasized Kami's opinion that they hadn't done anything evil until that point in the series. That is something that made them very unique when considering the bulk of the villains that author Akira Toriyama created throughout the manga.
Final thoughts
Android 18 was never truly evil in the main Dragon Ball timeline, and that was even emphasized by Kami and Krillin in the Cell arc. However, she joined Goku's side when Krillin spared her life, and the latter and Android 18 began to build a relationship in the seven-year time skip between the Cell and Buu sagas.