Ayame Soma is the older brother of Yuki Soma by ten years and the bearer of the Snake spirit in the Soma family's zodiac curse. Standing 175 centimeters tall, he has long, light grey or silver hair and distinctive gold eyes. His appearance is striking and elegant, with Tohru Honda once noting that he resembles an adult version of Yuki, though their personalities could not be more different. Ayame's personal style is as flamboyant as his character, often wearing self-designed, Chinese-inspired outfits that reflect his profession as a tailor and shop owner.

Ayame is defined by his exuberant, theatrical, and deeply self-centered personality. He carries himself with an almost royal air, speaks dramatically about himself, and has a seemingly unshakable confidence that the character Ritsu Soma admires as being off the charts. Despite this outward vanity, Ayame possesses a profoundly empathetic and contemplative nature beneath the surface. His antics frequently exasperate those around him, including his brother Yuki and cousin Kyo, whom he enjoys provoking with nicknames like Lucky Kyo. Ayame also has a playful, often performative relationship with his best friend Shigure Soma, with the two frequently engaging in exaggerated bromance scenes that confuse Tohru and irritate Yuki, Kyo, and Hatori. A notable aspect of his personality is a certain perverse streak; his fashion designs cater to what he calls mens fantasies, leading his brother to declare one of his suggestions a crime.

Ayame owns and operates a successful custom clothing shop named after himself, specializing in romantic costumes such as frilly dresses and maid outfits. He founded this business with the desire to create something that would not exist without him, pouring his creative energy into designing the garments. His work is a testament to his flair for fashion and his skill as a designer and tailor. He shares this enterprise with Mine Kuramae, who serves as his seamstress and eventually becomes his significant other. Their partnership is built on mutual passion for design and deep understanding; Mine is one of the few people who knows the secret of the Soma curse.

The most significant and complicated relationship in Ayame's life is with his younger brother, Yuki. During their childhood, Ayame was largely indifferent to Yuki, a neglect that cut deep. The defining moment of their early rift occurred when Yuki, suffering under the abuse of Akito, pleaded for Ayames help, only for Ayame to coldly dismiss him. This act of abandonment is a source of profound regret for Ayame, who eventually becomes obsessed with repairing their fractured bond. His attempts to connect are often overly dramatic, invasive, and overwhelming for the reserved Yuki, yet they stem from a sincere desire to make amends. Over time, as Ayame persistently demonstrates his remorse and willingness to be present, Yuki gradually begins to accept him, admitting that Ayame is somewhat reliable and eventually making efforts to understand his eccentric brother. This reconciliation is a central part of his story arc, showing his growth from a neglectful sibling to a committed, if still overwhelming, older brother.

Ayame is a key member of the Mabudachi Trio, the close-knit group of the three oldest zodiac members, alongside Shigure Soma and Hatori Soma. He and Shigure often indulge in their shared eccentricities, while Hatori acts as a restraining influence whom Ayame deeply respects and obeys without question. His high school years saw him serve as the student body president, a position where he leveraged his natural charisma and wordplay to modernize school traditions. Unlike many other cursed members, Ayame is one of the few whom the family head Akito finds unbearable and thus never physically or mentally abused.

The curse of the Snake makes Ayame highly sensitive to temperature changes, as he is cold-blooded like his zodiac animal. Exposure to cold weather or even a light wind can trigger an involuntary transformation into a long, thin white snake with gold eyes. He needs warm conditions to revert to human form and is also prone to illnesses like colds and the flu. To manage this, he always carries an umbrella for sun protection and often relies on cars for transportation to avoid transforming. Midway through the series, his curse is broken, and he is the fifth zodiac member to be freed. In the moment of his liberation, he immediately embraces Mine and declares his love, finally able to hold her without transforming.