In Chapter 1058 of One Piece, which released on August 29th, fans saw one of the most unlikely alliances formed between Crocodile, Dracule Mihawk, and Buggy the Clown. This alliance was the formation of the Cross Guild, an organization of bounty hunter pirates that hunts down Marines.
This was the idea of Crocodile, who formed the group alongside Mihawk. However, Buggy, another member of the guild was placed at the center of the poster and so the World Government believed him to be the leader which made him one of the Emperor of the Seas. While this is no doubt a comedic moment, it has shown fans unlikely allies - something recurring in many shonen anime.
Rohan Kishibe Becomes Close To The Other Stand s
While Rohan is recognizably one of the main of JoJo's Diamond is Unbreakable cast, he wasn't always one of the good guys. In fact, given how terribly he tormented Koichi it didn't seem likely fans would see Rohan again.
However, he quickly has a turn around and becomes close to the other Stand s as well as one of the main characters (though he doesn't get along well with Josuke). Still, he played a vital role in the final segment of the series against Yoshikage Kira.
Scar Never Felt Like The Bad Guy
Scar, from one of the Fullmetal Alchemist Brotherhood, never really felt like the bad guy. At least, he never felt nearly as bad as the Homunculi. However, fans began to question that when they found out more regarding his backstory and that he was the one who had murdered Winry's parents.
Despite the differences he faced with the Elric brothers, in the end Scar was able to come out on the side of the protagonists to fight against the Homunculi. While he doesn't totally forgive Alchemists, he still has incredible character development.
Piccolo Sees A Common Enemy
Dragon Ball is full of unlikely allies like Vegeta and Majin Buu, but in truth, Piccolo was even more unlikely than most of the others. While Piccolo himself hadn't committed as many atrocious deeds as his father (and former incarnation) he still put Goku through terrible pain, nearly killing him in their match.
Despite Piccolo being built up previously as this terrible villain, he was willing to put aside his differences to take out a larger threat. Even after toppling Raditz and hearing about two more Saiyans, Piccolo decides to help the others in taking them down. This triggered his development and his relationship with Gohan that would lead to one of the most compatible duos in Dragon Ball.
Orochimaru Survives Death And Returns
There are plenty of menacing villains in Naruto, but none left quite the impression that Orochimaru did in the first part of Naruto. Orochimaru seemed a hopeless case and at one point fans even believed him to be dead.
However, thanks to the curse mark he left in Anko, he was able to survive and return. What stunned fans the most was his eagerness and willingness to help Sasuke and the others. Without Orochimaru, Sasuke likely wouldn't have aided in the war, nor would they have the help of the former Hokages thanks to the reanimation jutsu.
Crocodile Saves Luffy's Life
While the infiltration of Impel Down saw Luffy allying himself with plenty of old foes that shocked fans, there was no more unlikely than one of the most powerful villains of One Piece, Crocodile himself.
Thanks to Ivankov knowing some secret of Crocodile's, Crocodile was more held-back and didn't once try to betray Luffy. In fact, he even saved Luffy's life in the battle of Marineford. Afterwards, Crocodile surprised fans further with even more shocking allies of Dracule Mihawk, the world's strongest swordsmen, and Buggy the Clown who they accidentally made one of the Four Emperors of the Sea.
L And Light Find Common Ground
Light Yagami's opponent was clear very early on in Death Note, and that was L, but the fact that the two would one day be allies was pretty unimaginable, especially when they were battling against each other the whole time.
The first time they team-up is of deception, with both of them investigating each other. However, the second time is far more genuine since Light erased his memory. Many fans believe the two cared for each other as true friends, but it's impossible to say for sure given how badly the two of them wanted to defeat each other.
Naruto Forgives And Befriends Kurama
Kurama, also known as the Nine-Tailed Fox, was the creature responsible for laying waste to the Village Hidden in the Leaf and for killing Naruto's parents. Not only that, but due to the fox being sealed within Naruto, it also made Naruto a target of hatred in his village.
Despite all of that, Naruto still chose to forgive Kurama and befriend him. Throughout most of Naruto, Kurama is seen as this vile source of power that Naruto shouldn't over rely on, but he eventually learns that his true task wasn't to master or resist Kurama but to become one with him and ally himself with him.
Zeke And Eren Yeager Are Temporary Allies
The team-up of two of the Attack on Titan. These two had been head-to-head as enemies since the moment Zeke first appeared and when Zeke revealed his intentions of the euthanasia plan, many fans found it more odd that Eren would ever ally himself with Zeke.
This of course turned out to be a farce, but Zeke desperately wanted Eren to see his ways but instead ended up seeing Eren as the true monster of the story. While the two were back to where they started as enemies again, it made it all the more unlikely that they had become allies to begin with.
Takasugi Shinsuke Gets A Tragic Backstory
Takasugi was initially set up to be the primary antagonist of Gintama, so when it turned out that he wasn't, it became rather surprising that he transformed into one of the most valuable allies in the final segment of the series.
Understanding the pain and motivations of Takasugi in the Shogun Assassination arc involved some of the most heartbreaking scenes from Gintama. The relationship between him and Gintoki was explained and shown so well and was perfectly reflected in their battle. It was proof that only these two would and could be the only ones to take down Utsuro.
Frieza Does What It Takes To Survive
Out of all the villains in Dragon Ball, it's hard to top Frieza. He is without a doubt the most menacing and resilient characters the heroes have ever faced. Yet despite this, he was still willing to become allies with his old enemies for the Tournament of Power. Though he nearly betrayed them, he saw his best option of survival was to remain with them.
He displayed himself as an incredible ally as one of the most vital of the tournament. However, while he fought hard alongside the others, he's back to his old life again and is once more scheming. This time his plans seem bigger, and he no doubt will be an enemy of Goku and Vegeta again.