Zeus, also known as "Zeus the Thundercloud," is an extraordinary and interesting character in the One Piece series. He was originally crafted by Charlotte Linlin, much better known as Big Mom, as a homie. Zeus is an intriguing character in terms of change throughout the story—from antagonist to supporting protagonist. This is not the only change that happened to Zeus, for he is merged with Nami's Sorcery Clima-Tact, which greatly boosts her powers of weather manipulation.
Having been a homie, Zeus himself was created by the powers of Big Mom from the Soul-Soul Fruit—this let her put souls into lifeless things to give them life and special abilities. Resuming his old form, Zeus took on the form of a storm cloud; thus, Big Mom could summon him anytime she wanted. He hence acted as a means of transportation and a fearsome weapon in battle. What really made him such an invaluable addition to the arsenal of Big Mom was his ability to turn into and manipulate light.
The real change of pace for Zeus came with the Whole Cake Island arc when Nami, navigator for the Straw Hat Pirates, could briefly control him through her knowledge of the weather and the promise of thunderclouds that she could provide. This set up the eventual scenario where Zeus would defect from Big Mom's service. This inner struggle of Zeus is, therefore, a very good example of just how complex his character really is: torn between strict obedience that he feels toward his creator and temptation to seek out Nami because of the powers related to weather that suited his nature as a thunder cloud.
Of all power-ups the Straw Hat crew received, Zeus's fusion with Nami's Clima-Tact proved to be the most influential. This greatly boosted Nami's fighting potential by merging Zeus's ability to control lightning directly from her weapon. Since their fusion, the ability of Zeus and the Clima-Tact synergy has been shown in many battles, displaying the vastness this mix of abilities can possess.
One of the most memorable things regarding Zeus at the moment is the fact that nobody really knows whether he is alive or dead after Big Mom lost. Though Devil Fruit powers normally shut down when the user either dies or becomes incapacitated, Zeus still acts as part of Nami's Clima-Tact even after Big Mom's presumed death. It has propelled fans into speculation regarding the nature of homies and whether the soul infusion is permanent within the One Piece world. Some theories are holding that either Big Mom's strong will or, likewise, that the properties of the Soul-Soul Fruit can let her creations persist in their own right, independent of her.
Zeus's existence has been confirmed in the recent story arcs, especially in the Egghead Island arc, in which Nami keeps using his powers. Why he does not seem to cease functioning should raise interesting questions about the nature of souls in the One Piece world and whether homies would one day reach true independence from their creators.
From becoming a cloud to the intricate design as Zeus, part of the Clima-Tact, it has made him a favorite source for so many fan arts and merchandise. To this, add an expressive face and the visual flair with all the lightnings; the result is fans adoringly in love with him. In the anime, Zeus is voiced by Yū Mizushima in Japanese and Kevin D. Thelwell in English.
Zeus does get relevance even in the One Piece Card Game, appearing as a Character Card in many of the sets, such as "Starter Deck 7: Big Mom Pirates." With these cards, gamers could make characters with powers related to thunderclouds, showing how relevant Zeus is to the power balance of the series.
On a larger scale, Zeus represents change and the possibility for redemption throughout the One Piece series. His turning from a tool for an Emperor of the Sea into an extremely valuable ally of the Straw Hat Pirates resonates with the series' themes of freedom and the power of forming new bonds. In short, Zeus points to a case that Artificial Beings with complications do exist in the One Piece world: problems of consciousness, loyalty, and what makes someone himself.
Zeus has been involved in some of the most crucial fights, most significantly in the escape from Whole Cake Island. Then there's one memorable scene when Nami used Zeus to strike a strong blow on Big Mom herself; it had been a tumultuous moment of action that unravels the potential of their partnership and the irony of Big Mom's own creation being used on her.