In One Piece, it's not as simple as heroes vs. villains, one clear-cut side vs another. This means that some characters like Sabo are friendly to Luffy, but ultimately owe their allegiance to other leaders or groups. Sabo may help Luffy sometimes, but he's got his own mission, so he's not about to join the Straw Hats.
One Piece also depicts Sabo as a young man who restarted his entire life and made something of himself. He was a renegade noble in his homeland and was Ace and Luffy's brother, but unlike his brothers, Sabo nearly died at sea and lost his memory for a time, carving out a whole new path for himself afterward. One Piece fans can thus compare Sabo to similar characters in other anime franchises – that is, heroes who sometimes aid the protagonist but have their own path.
Sabo Developed a Fighting Style Called Ryusoken
10 Kurapika Kurta Helped Gon Fight the Phantom Troupe
Hunter x Hunter
When Hunter x Hunter launched with the Hunter Exam arc, there were four main heroes. Protagonist Gon Freecss had Killua, Kurapika, and Leorio by his side, but they wouldn't remain a permanent squad for long. They had their own goals and missions to pursue, and only Killua remained by Gon's side the entire time.
Kurapika Kurta was a circumstantial ally for Gon in the Yorknew City story arc, since Kurapika had a serious grudge with the Phantom Troupe organization. However, like Sabo in One Piece, Kurapika only aided the hero when it was convenient, since he had his own mission and never meant to join the hero's main squad. Kurapika is the hero of his own story, just the way Sabo is the hero of his own story after joining the Revolutionary Army to overthrow the World Government.
9 Uryu Ishida Sided With Ichigo to Save Rukia & Orihime
Bleach
Protagonist Ichigo Kurosaki became a substitute Soul Reaper in Bleach's first episode, and his Quincy classmate, Uryu Ishida, wanted to be his unfriendly rival. Uryu thought he was "supposed" to hate Soul Reapers like Ichigo, but he and Ichigo couldn't help becoming good friends anyway. They also shared goals when the time came to rescue Rukia and later, rescue Orihime Inoue as well.
It was the Thousand-Year Blood War arc that drove Uryu and Ichigo apart. Like Sabo in One Piece, Uryu Ishida owed his allegiance to a completely different group than the hero – in this case, the Wandenreich, the hidden Quincy empire. In fact, that led Uryu to evidently betraying Ichigo and fighting against him in the war.
8 Katsuki Bakugo Was Ready to Die For Deku
My Hero Academia
Katsuki Bakugo's Final Fate is Still Uncertain
Even if Katsuki Bakugo had a much nastier temper than most Sabo-like anime characters, he still fulfilled that role in My Hero Academia's story. Bakugo was Izuku's classmate at UA, where they constantly feuded as shonen rivals to see who would become the next #1 pro hero after All Might.
Izuku and Bakugo butted heads constantly, and of course, only one of them could be #1. Still, even if they were competing, they couldn't help but fight together against their true enemies, such as the League of Villains, making them proper allies when necessary. They even shared One For All in the first MHA movie, and Bakugo was eventually willing to take a blow for Izuku's sake.
7 Monkey D. Luffy Was Everyone's Sabo
One Piece
There can be more than one Sabo-type character in the same anime franchise. Just the way Sabo sometimes helped Luffy when their paths aligned, protagonist Monkey D. Luffy was always ready to support his new friends on various islands, even if their end goals differed.
An early major example was Princess Nefeltari Vivi, who aimed not to roam the seas, but help lead her kingdom. Luffy knew he and Vivi would soon part ways after Crocodile's defeat, but he still helped her, and he accepted reality when Vivi opted to not board the Going Merry to officially join him.
6 Mary Saotome Gambled With Her Rival, Yumeko
Kakegurui
Kakegurui is One of Many Great Gambling Anime Series
The gambling anime Kakegurui depicted a highly competitive, dog-eat-dog private school called Hyakkou Academy. Protagonist Yumeko Jabami was always happy to gamble with anyone regardless of rivalries or personal politics, and that included her new frenemy, Mary Saotome.
Mary aimed to become the student council president while Yumeko merely gambled for her own pleasure, and the two girls were only loosely united as allies. Still, Mary wasn't above gambling alongside Yumeko to take down their most fearsome rivals during the election tournament, and neither would have gotten very far without the other's aid. Luffy and Sabo were heroic wild cards in One Piece, defying the rigid world order, and Yumeko and Mary were like that in Hyakkou Academy.
5 Aoi Todo Took Down Hanami With Yuji
Jujutsu Kaisen
Jujutsu Kaisen introduced two rival sorcery schools, with one each in Tokyo and Kyoto. Those schools' students met up in a would-be tournament arc where the students were expected to fight curses, but instead, the students fought one another. Aoi Todo, a Kyoto student, personally battled protagonist Yuji Itadori in one such clash.
Aoi and Yuji soon set aside their differences to fight their common enemy, Hanami the curse. Yuji and Aoi became best friends based on their shared experience. Though their friendship was only surface deep and they have rather different life goals, they can still count on one another when things are dire, making Aoi Yuji's own Sabo. Their life paths diverged, but Aoi will make sure to have his comrades' backs when it’s convenient.
4 Rem Sometimes Aided Light To Protect Misa
Death Note
Rem
Light Yagami Was Downright Evil in Death Note
The genius Light Yagami had few true friends or allies in Death Note. Instead, he tended to use people, from his lover Misa Amane to the Japanese police and even certain Shinigami. The most Sabo-like of these characters was the Shinigami named Rem, who was attached to Misa.
Rem was not Light's friend or protector, but she was connected to him via Misa, and Light took advantage of that a few times. Rem's goals were totally different than Light's, but she was willing to play her part in his plans all the same. Rem did that to protect Misa, but tragically, Light used Rem's protective feelings to kill her, L, and Watari in one fell swoop.
3 Jellal Fernandez Became a Loose Ally of the Fairy Tail Guild
Fairy Tail
At first, Jellal Fernandez the wizard was an antagonist in Fairy Tail, but he was later redeemed and got another chance at life. In fact, he was one of several villainous wizards who decided to form an antihero guild called Crime Sorciere, a small guild friendly to the Fairy Tail guild. Like Sabo in One Piece, Jellal was a childhood friend that resurfaced and joined the main heroic group.
Jellal usually wandered the continent Ishgar on his own mission with his two guildmates, but he would also aid Erza, Lucy, and the other Fairy Tail wizards if their paths ever crossed. It helped justify the heroes' habit of showing mercy to their defeated enemies, a good spin on Fairy Tail's reluctance to kill anyone at all.
2 Askeladd Trained the Boy Who Wanted to Kill Him
Vinland Saga
In a bizarre twist of fate, the vengeful protagonist Thorfinn Karlsefni became the unofficial foster son of his father's killer. Thorfinn hated Askeladd for killing Thors, but Thorfinn had nowhere else to turn, so he joined Askeladd's band and learned how to fight.
Askeladd played his role as a bizarre boss and foster father to Thorfinn, though Thorfinn still tried to kill him regularly in official duels. Still, the two of them had differing goals, with Thorfinn fixating on revenge while Askeladd was the opposite, striving to protect other people at any cost – in this case, the Welsh people. Sabo fought the World Government and its Five Elders to bring about freedom, and Askeladd did the same in medieval Europe against King Sweyn.
1 The Reborn Greed Teamed Up With Edward Despite Their Differences
Fullmetal Alchemist: Brotherhood
The conniving villain Father had seven homunculus "children" modeled after the seven deadly sins, though not all were loyal to him. Greed defied Father and lived on his own until he was captured, melted down, and reborn in Ling Yao's body. The new Greed then broke away from Father a second time, determined to hoard treasure and fame once again.
The new Greed actually agreed to team up with Edward Elric despite their differing worldviews and goals. They both wanted Father taken down, albeit for totally different reasons. In the end, Greed died for the heroes' sake on the Promised Day, making him the noblest homunculus and a true Sabo hero at heart. And like Sabo, Greed fought to prevent a tyrant from taking over the world, protecting everyone's freedom in the process all over Amestris.
