Gyro is a master of the Spin and an executioner hailing from the Kingdom of Naples. He joins the Steel Ball Run race to win amnesty for a child he is assigned to execute. Gyro's signature weapons are his special Steel Balls that produce and manipulate the Spin - the mastery of which later allows him access to the senescence-inducing Stand Ball Breaker.
Gyro is a man of average to above-average height and medium to athletic build. He has long hair that reaches mid-back, light-colored eyes, and square patches of facial hair lining his jaw, four on each side. He either wears grills or has chiseled into prosthetic teeth the phrase "GO! GO! ZEPPELI".
Throughout the Steel Ball Run race, Gyro wears a variety of outfits to suit the weather of the current location. However, they all maintain the same key elements and motifs of his wide-brimmed hat and slit goggles, a dark shirt studded with miniature steel balls, a cape wrapped around his shoulders that splits into three segments, and his large belt with special holsters for his two Steel Balls.
Gyro initially appears as an aggressive contestant in the Steel Ball Run race. Unlike other competitors, Gyro looks to seize the first place above all else, rushing ahead of everyone then fending off anyone who challenges him. He also has a tendency to take dangerous shortcuts. Gyro is a rude man, deriding the vast majority of those he meets with insults and mocking commentaries. Even with his closest friend Johnny Joestar, Gyro doesn't mince his words and sometimes argues with him. Moreover, Johnny only made a lasting impression on Gyro through his dogged stubbornness and otherwise looked down on him during their first meeting. The only person for which Gyro had any degree of respect is his stern father Gregorio Zeppeli. Gyro's overconfidence extends to his fights, during which Gyro is prone to mock his enemies in some way or say something brash. For instance, he openly mocked Mountain Tim's "ridiculous" hat.
Gyro is particularly proud of his mastery of the Spin, a family technique involving the rotation and throwing of steel balls to various effects and hails the Spin as the acme of human skill, this pride is, to a degree, justified when the Spin manages to overpower D4C Love Train. However, as a teacher he seemed to be somewhat begrudging, only bothering to teach Johnny the basics of the Spin and introducing him to the Golden Rectangle when they were threatened by a new enemy.
As an executioner and otherwise confrontational man, Gyro is not afraid to use violence even in a lethal fashion. However Gyro doesn't have the same ruthlessness as Johnny and initially doesn't seek to kill his enemies if he deems it unnecessary. Notably, Gyro did try to discourage a thief from fighting with him and only used his Steel Balls to make the man shoot himself if he ever drew his gun, instead of directly killing him.
Gyro nonetheless possesses an altruistic side, and likes to help anyone who needs his assistance, most notably the paraplegic Johnny to whom he taught the Spin technique and helped acquire the Holy Corpse Parts, or Marco, the helpless child whose death sentence Gyro seeks to appeal by winning the Steel Ball Run. Gyro would often clash this side with the authority of Gregorio Zeppeli, who disapproved any display of sentimentality in life and ultimately defied him by going to America.
Johnny originally said that Gyro didn't have the drive and determination necessary to get things done. The jockey argued that because Gyro inherited everything he had as an upperclassman and heir of the family Spin technique, he didn't have the kind of selfish hunger born from suffering which was crucial in the race. True to that, Gyro Zeppeli initially raced out of altruistic concern for Marco, and primarily relied on tricks to prevail in the race. During his battle with Ringo Roadagain he bent his original motivations into a more personal goal, the path to see for himself whether Marco deserved to be executed and and who exactly the Corpse was. After that, Gyro switched to a slightly less cocky behavior, and focused seriously on his battles. In his horse riding, Gyro switched to a more personal style, instinctively choosing his own route instead of the "shortest path", enabling him to even outmatch Diego in the race.
Out of combat, Gyro also possesses an eccentric personality and is particularly bombastic. Gyro has a penchant for gags, involving puns or an inexplicable brand of humor from bad puns to skits defying all logic, frequently telling such jokes to Johnny in the spur of the moment and created a song about Mozzarella cheese, singing it to Johnny and being happy that he appreciated it. He also has a fondness for dramatic gestures and quotes, saying that the Goddess of Victory was riding with him and that she would retract her favor if he ever let another woman ride with him. Unlike Johnny, Gyro frequently grins, exposing his metal teeth in the process. The mere fact that he engraved his teeth with the message "Go! Go! Zeppeli" already exposes his ostentatious nature. Humorously, Gyro also keeps a pink teddy bear with him, being fond of it enough to keep it even during the Steel Ball Run, although he leaves it at one point. However, mimicking his own father, Gyro can be stern and dignified when he talks about the Zeppeli Spin technique.
Heavily influenced by Gregorio's teachings about the uncertainties in life - using a "tennis ball over the net" metaphor - and the Steel Ball's power being nothing short of miraculous, Gyro has a somewhat optimistic outlook on life and is convinced that he can overcome setbacks, even if they'd need a miracle to overcome, as long as he follows a virtuous path. Nonetheless, following the "tennis ball over the net" belief, Gyro is aware that failure is just as likely. This ideology is repeatedly somehow confirmed with numerous coincidences and miracles helping him throughout his journey and alternatively working against him, culminating in Marco being freed without his intervention but dying of a cold later.
Gyro is a womanizer, one flashback narrating an affair with a patient and he is shown flirting with pretty girls. On the other hand, the first time Gyro and Johnny meet Lucy, he refuses to let her ride with him and states that "no woman (will) ride my horse". He later explains that "Lady Luck" would be jealous if he let "another woman" ride with him.
Gyro has a few tics of language. For instance, he has a signature "Nyo-ho-ho!" chuckle and he usually shouts out "ORA!" when he hurls a Steel Ball in combat, reminiscent of the Stand Cries of the former Joestar Stands. Eventually, after Gyro's death, Johnny adopts Gyro's battlecry as Tusk ACT 4's own Stand Rush.
The complete guardian of the Corpse's eyes appears as a largely insentient, robotic humanoid figure. When Gyro departs this figure, it is divided, missing its left arm, leg, upper "eye" and the left plate of the two originally framing its head. A similar figure is seen once more when Gyro uses Scan, growing from his Steel Ball, in his battle against Ringo Roadagain.
- Main article: Ball Breaker
Ball Breaker manifests when Gyro finally achieves the "Golden Spin". The stand is a visualization of Spin energy unleashed from Gyro's steel balls, the sheer power of the technique manifesting itself into the form of a Stand. Ball Breaker embodies a vast force capable of bypassing dimensional barriers.
Gyro is an experienced and capable equestrian, competent enough to ride across many types of terrain and be a serious competitor in the Steel Ball Run race. His ability as a rider reached a new level after he entered a "real man's world" in his fight against Ringo Roadagain and he became able to instinctively choose the optimal path for his horse, an ability that seems on par with Diego Brando's own ability. His riding style can be summed up as aggressive; Gyro seeks to remain at the first place constantly, and takes dangerous shortcuts when he deems it necessary. When another rider challenges him, Gyro will actively try to get rid of him. His beloved horse is named Valkyrie. Gyro is also knowledgeable about horses, particularly Valkyrie, whose abilities and limits he can gauge at any moment.
- Medicine, Surgery and Anatomy: Trained by his father, Gregorio Zeppeli, Gyro is an accomplished surgeon, being able to make surgical operations on his own. This training also includes intimate knowledge of the human body Gyro uses in conjunction with the Spin in combat.
- Intelligence: Gyro is an adept tactician, being able to hold his own against several Stand users and outsmarting them in several occasions. Gyro has been shown to be able to use his surroundings, or even the enemy's own power to his advantage. Gyro is a worldly individual, possessing a range of knowledge, including in tracking, opera, paleontology, and mathematics.
- Gregorio Zeppeli: As Gyro's father, he was the only person to ever command respect and obedience to him. Their relationship was probably cold due to Gregorio wishing to throw away sentimentality from his life, thus never had a compliment for his son, nor did he give him gifts and send him letters. However Gregorio was still Gyro's Spin teacher and direct superior as surgeon and executioner, thus has authority over him, although Gyro still disobeyed him behind his back.
- Johnny Joestar: Gyro and Johnny are friends and partners in the Steel Ball Run and also master and apprentice in the art of the Spin. At first Johnny's determination got Gyro's interest, causing him to help him figuring out how to mount his Slow Dancer and start the race. After the first stage, Johnny wins the respect of Gyro, thus Gyro decides to teach him the Spin and they become partners for the rest of the race. As the stages progress their friendship grows. Despite their opposing personalities, causing regular clashes as to how to take on a difficult situation, Gyro and Johnny ultimately get along well and share many moments of friendship, culminating in them telling each personal secrets. Gyro notably likes to jest with Johnny and tells him bad jokes or miscellaneous songs that Johnny frequently pretends to appreciate. Due to their regular battles, Gyro and Johnny fight well together, and see each other as valuable allies. Their friendship is such that any one is ready to put himself in danger for the other, and Johnny notably abandoned his Corpse Parts to save Gyro's life, and has cried multiple times for him. When Gyro died, Johnny was completely devastated and Valentine exploited that bond to promise Johnny that another Gyro would walk in this world. Gyro's ghost salutes Johnny one last time and the latter would bring back his corpse to the Zeppeli family. Gyro's continuous support helped Johnny get out of his depression and enabled him to begin anew.
- Lucy Steel: Gyro and Lucy became allies, but Gyro had a cold attitude toward her, refusing her request of helping her and her husband and instead suggesting that she risked her life trying to steal the Heart from Valentine. Gyro nonetheless acknowledged her bravery and resourcefulness and entrusted the Right Eye with her, later asking Wekapipo to save her from Valentine.
- Wekapipo: Despite meeting in the Steel Ball Run race as long-standing enemies, Gyro and Wekapipo have a certain respect of each other's ability as both are proficient Spin users. Gyro revealed to Wekapipo that his sister was alive and well, having saved her life once. This revelation earned Gyro Wekapipo's help during the search for the Corpse Parts.
- Mountain Tim: Gyro only saw Tim as a rival in the Steel Ball Run race, deriding his hat when he first saw Tim. However, both come to see as allies during the fights against the Boomboom Family and Oyecomova.
- Diego Brando: Gyro and Diego are bitter rivals, as both repeatedly tried to outdo each other in the Steel Ball Run. Gyro thinks of Diego as the greatest threat for his goal of finishing first in the race and never ceases to antagonize or insult him. Diego won't hesitate to kill Gyro, but Gyro's moral code stops him from doing the same, and he only wishes to beat him up.
- Hot Pants: As one of the competitors in the Steel Ball Run race and a rival in the search for the Saint Corpse Parts, Gyro views Hot Pants poorly. Their first meeting consisted of Hot Pants attacking Gyro for wrong reasons, and Gyro never let up his antagonistic behavior after that, regularly insulting the horse rider and once stealing her food. Later on, Gyro remains in the dark about Hot Pants' true identity, while Johnny was able to forge a more understanding and sympathetic relationship.
- Sandman: Gyro and Sandman are rivals in the Steel Ball Run race, but initially act friendly with each other. Sandman bore no ill will against Gyro and repaid being made winner of the first stage in Gyro's stead with critical information during the fourth stage. However, the next time they meet, Sandman now worked with Valentine and tried to force Gyro and Johnny to give their Corpse Parts, going as far as trying to kill them. Nonetheless, Sandman was merely indifferent to what he saw as the struggle between white men.
- Pocoloco: Gyro thinks of Pocoloco as a dangerous rival and mistakes the latter's luck as talent, while Pocoloco sees Gyro as a mere stepping stone in the race.
- Boomboom Family: Gyro was initially cold and cautious to Andre Boomboom, and he was later proven right to act in such a way as Andre, along with his brother and father, attacked. Gyro thinks the whole family as idiots, though holds regard for their dangerous Stand abilities.
- Oyecomova: Oyecomova was an Italian assassin who attempted kill Gyro, Tim and Johnny, only to be defeated by their respective Stand powers.
- Ringo Roadagain: Ringo and Gyro were mortal enemies during their encounter. Ringo looked down on Gyro for being a "follower" but was impressed by his sudden growth, acknowledging his will during his last moments. Gyro returned the animosity and begrudging respect for the gunman.
- Funny Valentine: Valentine was Gyro's enemy in the search to obtain the Corpse Parts.
- “Nyo-ho ho ho~. (ニョホホホ~。)”—Gyro Zeppeli's signature chuckle.
- “We are both rivals, so I'll head onwards. The direction I'll be heading in though, is toward that son of a bitch!”
- “That boy... I will take the place of my father who has put his pride in the family line. This job is my duty... and that will never change... It hasn't in the past and it won't change from here on. But I just want consent! I want to make this duty the pride of my heart! Guilty or innocent! There needs to be consent! Pride and honor cannot exist without consent! I will put my life on the line for pride and honor. Isn't there a way? Not all laws are justice! I cannot agree with putting that boy to death!”
- “If I may, father… sentimentalism…? That’s not it. Plus, that bastard, he thinks I’m a conformist? Fuck that… big-headed asshole talking big, is he? I just want to understand. Does Marco really have to be executed. What the hell is the identity of the Corpse that Johnny wants to find? My path to understanding is the ultimate priority! Or else, I’ll never be able to move forward! Nowhere! Not even the path to the future! I won’t be able to pursue it! That’s why I joined the Steel Ball Run race! I can see it! I’m beginning to see it, father! I’m getting the sensation of victory!”
- “"I don’t have my Steel Balls this", and "you can’t win with your nail bullets that"… Are you underestimating my rotations? Are you looking down on the 250 years of the Zeppeli Family’s history? What I’ve taught you is still just the basics!”
- “'Lunedi', Monday! 'L-U-N-E-D-I'! 'Martedi', Tuesday! 'M-A-R-T-E-D-I'! 'Me...' What was it again?! I forgot! Ahahahahaha! What was it? What was it? Ehehehehehe! Um, what was it again? Eeeeeeeeehehehehehe! I completely forgot! Aaahahahahahaha! 'Domenica', Sunday.”
- “I’ll tell you (and only you) my real name. “Gyro” is a pet name, or rather a nickname. My real name is “Julius Caesar Zeppeli” My father gave it to me… even my younger brothers don’t know that name… you’d better not tell anyone.”
- “The Golden Rectangle, Johnny. Got it? What kind of energy does the rotation gained from the horse have? No one knows. One’s even seen it, that Spin. “Can I really do something like that myself?” If you’re thinking that right now, then know that the only way is with the Golden Rectangle. Make your horse run with that form. If we can obtain that rotational energy from the horse… It can only be with the horse in the form of the golden rectangle. Make the horse run in a way the horse itself thinks is good… like how a horse feels happy naturally running on the grass… like you’re thanking the horse itself for being born and coming to be here in this world under the sky. That is the time it will make the Golden Rectangle. Then we’ll definitely be able to win.”
- “Johnny! Lesson 5!... yeah… I’m sure that’s what we’re on now. The next one’s lesson 5! I always tried to take the fastest shortcut in this Steel Ball Run race, but, “the shortest route was a detour. It was the detour that was our shortest path”. It’s been true the whole time we’ve been crossing this continent. And because of you, we were able to take that route.”
- “If that’s how it is… I’m okay with it… my real name… you promised, right…? Don’t tell anybody. See ya… take care. (そうゆう事なら…そうゆう事でいいんだ…オレの本名は…約束したよな………誰にも言うなよ。じゃあな…………元気でな。Sō yū kotonara… sō yū kotode īn da… ore no honmyō wa… yakusoku shita yo na……… darenimo iu na yo. Jāna… genki de na.)”
Creation and Development
Araki personally liked the Jonathan–Zeppeli relationship from Phantom Blood and wanted to retell it again for a longer coming-of-age story. He chose to make Johnny and Gyro around the same age so they could be less formal and more friendly than their original counterparts.
- In the Italian edition of SBR, Gyro's name is written as "J.Lo", in a reference to American Latina singer Jennifer Lopez. This is also a slight pun on the fact that the pronunciations of "Gyro" and "J.Lo" in Japanese are almost identical.
- In the French edition of SBR, Gyro's name is written as "Jayro".