As I had said back during my overview of the character betrayal trope cliché, I briefly mentioned the subject of villains gaining redemption. Although I stated there that a villain becoming good could be considered a part of that trope based upon the story, I failed to mention just how big of a juggernaut this writing trope really was on its own. The trope of reforming a villain has become huge in literature and other sources of media in the recent two decades, all because of a growing market for more diverse character driven story lines. Due to this, the trope has become wildly popular among writers, who use it to experiment just how diverse they can make a seemingly simple character. Additionally, villainous redemptions means expanding the hero's team to include a new quirky cast member, who is a reformed villain. Redemption arcs to writers is like eating an entire can of Pringles. Once you use the trope, you cannot help using it again.
The basic setup of these story arcs are quite simple to understand as well. After the villain goes through some type of life changing traumatic event, they end up having to make an alliance with the heroes in order to survive. While in this alliance, the villain slowly comes to realize their motivations may have been flawed, and go soul searching to find out who they really are as a person. This is usually motivated by the friendliest character, who can see the good in all people, even if they fight from opposing sides. Despite some initial hesitance by the heroes, the villain slowly becomes more and more a part of the group, to the point where the alliance does not seem to matter much to them anymore. Then during a climatic event in the villain's storyline, they almost take a heel turn back to the dark side, only to find they are no longer happy there. They denounce their villainous status here and become a true member of the team. By the end of this storyline, the former villain is either a full blown hero or an anti-hero balancing out both the good and the bad of their nature. Due to the appeal of the storyline on paper, many authors love to explore this storyline with at least one of their villainous characters. After all, doing so could open so many doors for the redeemed character, as well as for the main cast. Impossible feats become completely plausible, given you give the right amounts of imagination and dedication to the story. To most, there is nothing but good things to come when using this trope. Well, that is if you are doing it for the right reason, developing a character, instead of doing what the majority chooses to do instead.
A majority of writers use this trope as a safe get of jail-free card. They feel it is a safe place to take the plot so the audience can still stay invested without taking too huge of a risk. However, developing these plots are far from easy. In order to redeem a villain fully, there are many factors you have to balance out. The character has to have a realistic reason for wanting to make the switch, such as seeing their superior being in the wrong with how they are handling the main conflict. Peridot from the show Steven Universe illustrates this part of the trope well through her own redemption arc, after she came to realize the Diamonds, her superiors, did not care about Earth, a planet Peridot had grown to love for its organic beauty. All of the main cast almost have to buy into said villain's redemption realistically, so they are not out of character or at worst look like idiots. Crona's temporary redemption arc in the Soul Eater manga series works with this factor extremely well by first gaining the trust of the not always trusting Maka, whom had seen Crona's true wavelengths previously. Hence, her friends soon follow with trusting Crona, which is not at all out of character considering how strong Maka is with this ability. You then have to make the audience buy into the redemption, leaving no room for doubt that the character could become evil once again. The best example I have for this part of the trope is the transformation of Shadow from a villain during his first appearance into an anti-hero in all future appearances in the Sonic the Hedgehog franchise. Since his whole villainous motivation was to avenge his friend Maria, the audience can easily buy into his change of heart after remembering the last thing Maria wished for him before she died and that was to protect Mobius. Get even one of these elements wrong and you fall into cliché territory with this trope.
Missing the true point of a redemption arc, as well as its massive usage, is how it becomes a cliché. It is then that your redemption story becomes the eyesore of literature and easy competition against some of the worst clichés out there. At that point, you only used the trope for an easy get out of jail free card. Your villainous character has no realistic motivation to join the good guys. Heck, if you messed up on this trope badly enough, you could make them into a flat character or worse more evil than before. The audience will be annoyed every single time, not wanting to witness another second of the train wreck you created. Just because something looks easy does not mean you should try it for yourself without looking into it first. It would be similar to cliff diving for the first time and not checking for any hazardous rocks beforehand. No one wants to hit that kind of rock bottom.
If you are going to use a redemption arc, only do it if you think it will work for the particular character you have in mind. After all, you have to convince an entire audience that someone who had tried to kill the heroes time and time again actually feels remorse towards their actions. Just doing it for kicks is always going to end badly. The same philosophy can apply to any other cliché as well.