For some stories good and evil is as good as black and white. You have your good guys, and you have those crazy bad guys up there on Death Mountain. This sort of character doesn't believe that. Instead of enemies on those scary slopes, they see potential friends.
Instead, some characters are asking, Why are we enemies anyway? Has anyone ever tried talking things out? Does The Dark Lord even have any friends? Maybe if they got to know them a little better they might even turn out to be a decent person." So they try it out. They Befriend The Enemy.
A character who Befriends The Enemy is basically planning to become something of a Morality Pet to try and make a villain or antagonist change their ways. This has about a 50/50 chance of success since often times the villain really is a loner, or they're suffering from some sort of trauma and they could be redeemed if they had some friends to support them. Just as often, it turns out that Status Quo Is God. The good guy is just being naïve, and the villain uses the attempt against them or to deceive them and get what they want. Then again, maybe the bad guy can't ever truly make a HeelFace Turn because evil is just too fun to give up. Although we've been talking about absolutes like good and evil here, it's important to note that they don't have to be the main villain.
Subtrope of Good Feels Good, and of The Power of Friendship. It has some overlap with Talking the Monster to Death, the difference being that here the character is just trying to become friends to try to turn them good, not necessarily convince them they're wrong. The opposite of this is Enemy Mine, which is where a villain persuades a good guy to work with them to defeat a common foe, either by pretending they've turned good or through Teeth-Clenched Teamwork. If the friendship sticks, it's an Odd Friendship.
A villain who stays evil after truly befriending a hero may be a Token Evil Teammate or Poisonous Friend. Compare Defeat Means Friendship, Tastes Like Friendship, and We Used to Be Friends, the last of which being when the bad guy was originally a friend before they turned. Attempting to romance a villain or antagonist to change them falls under I Can Change My Beloved by way of Love Redeems. See also Friendly Enemy, where the two sides maintain frequent sympathetic interactions despite still warring.
- DokiDoki! PreCure: Regina has been successfully redeemed by Cure Heart and the other Pretty Cures by befriending her more than once. The first time immediately after Cure Heart beats her in a fight. Regina has for various reasons turned back to evil several times, only for the show to to start their friendship over and have her turn good again.
- Dragon Ball Z: Hercule (or Mr. Satan, depending on which version you watch), knowing he can't beat Buu in a fight, instead befriends the Obliviously Evil Majin Buu, and eventually makes him realize that murder, wanton destruction, and turning people into candy and eating them is wrong. Notably, Piccolo was watching this whole process and commends Mr. Satan for this, acknowledging him as someone worthy of the title "World's Hero". This resolution doesn't last long. A trigger-happy outsider pisses Buu off to the point that Majin Buu's evil side splits from the original Majin Buu and becomes the new villain.
- Gatchaman Crowds: This is Hajime's solution to a lot of problems. At the beginning of the show after Hajime became a Gatchaman she befriends one of the "MESS". An alien, enemy the Gatchamen are fighting who absorb humans and cause them to disappear. Immediately after Hajime befriends one of them the entire species of MESS stop acting antagonistic towards the Gatchamen and they return all the humans they absorbed safe and unharmed. The other Gatchamen are utterly shocked after seeing how well it worked.
- In JoJo's Bizarre Adventure Phantom Blood, Jonathan Joestar attempted this with Dio Brando, very, very hard, but Dio is the ultimate Ungrateful Bastard; being nice to him results in him either thinking you're an idiot to be taken advantage of, or getting really angry and resentful. In Stardust Crusaders, DIO inverts this by inducing fierce loyalty towards him in people who weren't otherwise evil.
- Future Jojos seem to like this trope though it seems to shift into Defeat Means Friendship as many Jojo's become friends with initial enemies- such as Jotaro beating the crap out of Kakyoin who then joins him in his mission to fight DIO, Josuke fighting with Okuyasu who attacks him and then becoming best friends with him soon after.
- In Mahou Sensei Negima!, after some serious deliberation on the subject, Negi decides that he wants to be Fate's friend, but will still give him the fight he desires. As of UQ Holder!, which is set 80 years after Negima, Fate deeply treasures his friendship with Negi and will do anything in his power to save him from the Lifemaker.
- Soul Eater:
- This is the origin story for how Liz, Patty and Kid met. Liz and Patty were once petty thieves who would threaten people in alleyways and mug them for money. Then they tried to mug the reaper Death the Kid. This got Kid's attention since he just happened to really want a pair to work with him, and saves them from a group of thugs, and befriends them. They've since put that life of crime behind them, and their friendship helps keep Kid's debilitating eccentricities in check.
- Maka befriends Crona, who was acting antagonistically toward them under order of the witch Medusa, after realizing that Crona was raised in an environment where nobody ever cared or acted friendly. Maka had to synchronize souls to calm Crona down first because magic blood was making Crona insane, but Crona breaks down crying after being offered friendship and silently accepts Maka's friendship with a hug and a handshake afterward.
- In The Demon Girl Next Door, the titular demon girl Yuko confronts local Magical Girl Momo, declaring she intends to kill a magical girl and sacrifice their blood to her ancestor to break a curse on her family, but Yuko is so laughably weak she poses absolutely no threat to Momo. Momo takes pity on her feeble assailant and even tries training her; she has multiple reasons for doing so, but merely tells Yuko it's for her own safety. However, when Momo is training Yuko how to use magic, Yuko reveals she doesn't really have any dark or malevolent feelings towards people and the world, and just wants everyone to get along and be friends. In light of this, Momo begins trying to genuinely become her friend.
- In Pleasant Goat and Big Big Wolf: Mighty Little Defenders, after 14 long years and 19 seasons of constantly fighting each other, the goats and wolves finally become allies.
- In Birds of Prey, Black Canary attempts this with Lady Shiva. Shiva is interested in Canary because of her rapidly-increasing martial arts skill and wants to face her in a Duel to the Death and later comes to owe her an important debt. Canary tries to use this to befriend and reform Shiva, but Shiva knows this and actively resists.
- Happens a couple of times in The Powerpuff Girls (DC run). "Presents Of Mine" (issue #57) as Him cajoling Buttercup into using the money she was going to spend on the Professor on herself. But when he sees the Gangreen Gang stealing from a children's charity box, he joins the girls in kicking their butts ("Even I'd never stoop to that!!") In "Micro Managing," (issue #68) Mojo Jojo helps Blossom defeat the Micro-Puffs, who have brainwashed Bubbles and Buttercup into having a Napoleon complex. In "Smart And Smarter" (CN Block Party #59), Bubbles and Buttercup root for Mojo to beat Blossom, who has let being admitted to an advanced school go to her head.
- A common tactic of Wonder Woman, most famously with Paula von Gunther. It doesn't always work, and it doesn't always stick, but she'll frequently make the attempt.
- With This Ring: Due to Guy Gardner's comments about positive connections preventing criminal recidivism, Paragon!OL aims to convince supervillains to reform by helping and encouraging them to more positive or beneficial goals. He's this to Cheshire, the Terror Twins, Lex Luthor and Abra Kadabra.
- When Cheshire is sent to jail, OL encourages her to keep her nose clean, get a GED and helps her get transferred to a nice prison. He hires Lex Luthor's defense team to get her a reduced sentence.
- OL promises to get Abra Kadabra a magic teacher if he doesn't commit any crime for a year and encourages him with a beginner's book for explaining magic. He teaches Abra a few spells when the latter defends the prison staff in the New Years Belle Reve breakout.
- OL visits the Terror Twinsnote regularly in prison and explains to them how they make more money legally as opposed to robbing banks. OL encourages Thomas to get a GED to make his resume look better.
- With Lex Luthor, OL encourages him to research the Danner Formula in hopes that Lex could make Bio-Augmentation more safe and mainstream. OL points to him how magic can be innovative because its many uses are so ill-researched by most people.
- He heals Fabiao, one of Bane's henchmen, when he surrenders himself over to the police.
- In Danny Phantom fanfic ResurrectedMemories: Zigzagged a bit in this story, Ember is aware of this but Danny and the others aren't.
- This trope is played straight in the Alterien series.
- Even though Helena was Oberon's enemy after he allowed her friend, Hermia, to die, they later become friends.
- Oberon does this again with Titania, who initially believed he was ill-suited for his mission.
- Cassie from Animorphs befriends Aftran, believing that even if humans and Yeerks could never make peace, the two of them could.
- Prose Lancelot: An Older Than Steam example, Sir Lancelot manages to befriend Prince Galehaut of Sorelois, who at the time was at war with King Arthur over a disputed territory, which eventually resulted in a peace settlement between the warring royals.
- In The Saga of Darren Shan, Kurda Smahlt advocates this to avoid the prophesied vampire war... At least until the other side's Chosen One actually appears. Then....
- In Harry Potter after the events of the seventh books is established in the epilogue that Harry and his Bully Cousin Dudley become somewhat of friends and spend some time together as adults, mostly to make their respective children play with each other as family. In the sequel Harry Potter And The Cursed Child Harry and Draco are shown to be friends as adults.
- Power Rangers: Due to a growing friendship Bulk and Skull become subtly less antagonistic toward the rangers while they're in civilian mode over time. This becomes more blatant in an episode of Power Rangers Turbo where T.J. not believing Bulk and Skull would steal helps them find the thief who framed them. Afterwards Bulk says "T.J. is pretty cool", and Cassie replies that T.J. thinks the same of them.
- Star Trek: Deep Space Nine has Sisko trying to make peaceful contact with the Dominion. When the Klingons invade Cardassia, Major Kira has to make peace with Dukat. The man who oppressed Bajor. When Dukat joins with the Dominion, Sisko tries to make peace with the Klingons to counter the Dominion.
- Later on, Kira is sent to help Damar run a Cardassian resistance against the Dominion. Damar goes through some massive character development as he realizes what kind of things he'd done to the Bajorans in the past and what he's going to have to do to free Cardassia.
- "X Company" has a German radio operator attempt to pull this off with Neil. It doesn't work and Neil ends up having to kill him.
- Season 2 has Aurora befriending a Nazi officers wife to gain intelligence on her husband. Aurora ends up genuinely caring about Sabine and tries to turn her. Unfortunately Sabine feels betrayed and attacks Aurora instead
- Spike in Buffy the Vampire Slayer, what starts as an Enemy Mine situation between Buffy and Spike at the end of the second season as they both want to avoid the end of the world turns into a somewhat complex friendship between Spike and all other characters (except Xander) by latter seasons.
- Fire Emblem Awakening has a variant involving Tastes Like Friendship. Gaius, a Thief, is working for the Plegians in a mission to kill "the Exalt" the Yllissean leader, but he doesn't have the heart to be a part of killing her. If Chrom talks to Gaius he'll offer him sweets, and they instantly become friends and he joins your army.
- In Mass Effect 2, Commander Shepard can pull this with almost any mentally-unstable squadmate, but Jack stands out. Jack is a violent, Ax-Crazy criminal with a Dark and Troubled Past and Shepard can help her deal with her demons in a number of ways. Jack goes through several levels of resistance, first warning Shepard that she knows what s/he is trying to do and that it won't work, followed by (if Shepard is male) propositioning for sex (because she thinks that's the only reason a guy would treat her nicely), followed by acting like a Tsundere. If Shepard takes the time to help Jack work out her issues, and helps reveal the fact that she wasn't hated by everyone in her childhood, but the beloved crown jewel of an abusive supersoldier project (the scientists tortured her but took extensive measures to ensure her safety), she'll undergo serious Character Development and become a Badass Teacher instead. If Jack is romanced in that game, it works.
- The other standout is Miranda Lawson, who starts out as a high-ranking member of Cerberus, and quite distrustful of Shepard's methods and motivations. She states that she would have liked to have put a control chip into Shepard's brain when bringing him/her Back from the Dead, and would disobey orders if they went against Cerberus interests. The turning point comes when Shepard helps her protect her sister from their father, without any ulterior motives, something no one else had ever really done before, and the friendship becomes much more genuine. When the time comes to choose between Shepard and Cerberus, she chooses Shepard with very little hesitation. By 3, she has gone from a Knight Templar Ice Queen to an extremely Nice Girl and The Atoner, who almost begs Shepard for forgiveness for the control chip that she intended to put in originally and whose only goal is to continue protecting her sister.
- Averted with Morrinth and Zaeed. She's had over three hundred years to be a psychotic serial-killer/bitch, and even Shepard doesn't have the power or more specifically, time to dominate the dominator. Zaeed is more of a Affably Evil merc.
- In Dragon Age: Inquisition, an Inquisitor with high approval with Solas can inadvertently pull this trope, although only because they don't know his real identity until much later on.
- Shin Megami Tensei: In the main games (as well as some of the spin-offs), the player character can befriend demons and make them his allies to summon. Demons are very fickle though. What works to befriend one demon won't work the same way each time, and if they aren't loyal enough to you they won't do what you say. The games follow Grey and Gray Morality so while a demon's alignment might technically be considered "good"... it's really in a Knight Templar sort of way. Demons are always initially antagonistic towards you before they join you, and after you befriend a species of demon the rest of that species will go out of their way to give you gifts and avoid fights with you while telling you to "take care of their friend".
- Wild Arms 2: Ashley & company develop a friendship this way with Kanon. Kanon, a demon hunter, has made it her mission to assassinate Ashley who is possessed by the ancient demon Lord Blazer who Kanon's ancestor sealed away thousands of years ago. The team reluctantly fight repeated battles with Kanon, until Ashley manages to convince her that he's a good person, and asks her to join the group plus entrusting her with the responsibility of striking him down (and killing Lord Blazer) if he can't control the demon's influence any longer when this moment finally does arrive however she can't bring herself to kill Ashley as she's developed feelings of friendship with him and the other members of ARMS.
- Undertale: While all monsters can be spared by doing actions that cause them to like the protagonist, this trope is most apparent for Undyne and Asgore. Both attempt to murder the protagonist horribly, but can be spared and befriended like everyone else. Doing this is required for the Golden Ending.
- Pokemon Series: Blue is the rival character to Red Pokémon Red and Blue, where as in Pokémon Sun and Moon they Co-Head the Battle Tree, and are shown reminicing about their time as champions.
- BoxxyQuest: The Gathering Storm has this as a Running Gag. Pretty much every time the gang meets a new bad guy, Tyalie eagerly suggests they join the team instead of fighting. It never works out.
- In Stellaris, it is entirely possible to befriend a xenophobic empire. Likewise, if they fall under attack from another empire, you can come to their defense, which will improve relations with them. And if that empire becomes part of your Federation, or a vassal state, with the right amount of influence, you can convince them to let go of their xenophobic ways. This cant be done with Fanatical Purifiers, Driven Assimilators, Devouring Swarm, or Determined Exterminators though.
- Cucumber Quest Plays this for comedy. Princess Parfait seeing some good in the Nightmare Knight, says she's happy to have made a new friend out of him. This is utterly baffling to The Nightmare Knight who is so used to everyone fearing him for being the main villain that it leads to his first Not So Stoic moment in the comic. Parfait mistakenly taking this for meaning he doesn't know what the word friendship means draws up some pictures of them having fun to try and explain to him what friendship is. Then when the Nightmare Knight says he doesn't desire her friendship he ends up doing something friendly for her anyway when he secretly takes her letter that she wanted him to deliver to Carrot.
- In Goodbye to Halos, this is Fenic's standard policy.
Elly: Are you gonna try and be their friend?
- Pixie and Brutus: When Brutus asks her to show what she would do if a large, mean animal tried to attack her, Pixie asks the mean animal (really a teddy bear) to be friends instead.
- The American Dad! episode "Bully For Steve" has Stan take the role of a childhood bully in an egregious attempt to make Steve stand up for himself. An oblivious Francine suggests Steve try to make friends with his new bully. When he attempts to do so, Stan goes along with it... and then continues beating him up, scolding him for not getting the point yet ("You can't reason with a bully!").
- Gravity Falls: In "The Golf War" Mabel realizes it's a better idea to befriend her Rival, Pacifica, than to keep fighting over who is better, after seeing how ridiculous the Lilli-putt-ians get with their petty rivalry over who has the best hole at the local mini-golf course. Specifically, Mabel realizes this when some of the Liliputtians try to kidnap and kill Pacifica to impress her, so they can win a sticker.
- Hey Arnold!. Some episodes involving Harold, who is a bully to the other kids in his grade, are frequently like this. Arnold being an All-Loving Hero befriends Harold in multiple episodes. Even deciding not to rat out on him to the principal in one episode, and helping Harold lose a ton of weight he gained in another episode.
- Justice League: A variant In the episode Flash and Substance. It's shown that this is how Flash deals with at least one of his "enemies" James Jesse "The Trickster" who Flash has pacified by befriending him. When Batman and Orion threaten James in a bar Flash cuts in and stops them to talk things out. He points out to James he's off his meds again, and that he didn't even realize he was wearing his villain costume. James agrees to admit himself back into the hospital after he finishes his drink if The Flash will visit him and play "soft darts", and then tells The Flash about a plan by the other villains to attack him at the grand opening of the new Flash Museum. This is baffling to Orion who is used to using more violent methods to get information.
- My Little Pony: Friendship Is Magic: In Keep Calm and Flutter On, Fluttershy's plan for redeeming Discord amounts to treating him like a friend. It works despite his inherent "do whatever I want" behavior and inevitable betrayal because, to even his own surprise, he doesn't want to lose his only friend.
- The Simpsons. Bart's tried to befriend his bully and antagonist, Nelson Muntz, in some episodes. The first time to become popular, which resulted in Bart being bullied even harder when Nelson found out he was being manipulated. In later seasons however, Bart and Nelson have become friends over time, and Bart even calls him his other best friend in one episode.
- Spongebob Squarepants. In the episode F.U.N. Spongebob tries to befriend Plankton and asks him to play with him after seeing how Bikini Bottom treats him badly and calls him a loser. Plankton decides to go along with it, and use it as an opportunity to steal the Krabby Patty formula. After sharing a Friendship Song together, Plankton does become his friend for a time, but ultimately chooses to betray Spongebob and steal a Krabby Patty at the end of the episode because evil is just too fun. This kind of scenario has been recycled several times in the show usually with Plankton trying to exploit Spongebob in a new scheme.
- The Cattanooga Cats: At the end of a long day of a cat-and-mouse chasing routine, Motormouse will give Autocat a lift home.
- The eponymous Steven Universe has a tendency to resort to this, combined with a touch of Cuteness Proximity; Steven doesn't have a mean bone in his body, trying to befriend just about anyone, from jerky donut-shop clerk Lars Barriga to Peridot, an enemy Gem from Homeworld who had previously tried to outright kill him..
- This is what happens to Cyril Sneer in The Raccoons's as the show progresses. He becomes closer and closer with the heroes to the point of practically turning into the Token Evil Teammate in the final seasons.
- Rataxes in Babar gradually turns less hostile and tyrannical as he befriends Babar and family, it helps that his wife and son were already friends with Babar's wife and children.