Fohl is a demi-human of the Hakuko species, also known as the White Tiger clan, and is the older brother of Atla. He has black and white hair, thick round cat-like ears, and a striped tail. His blue pupils have vertical stripes, and his facial expression often appears wild and intimidating. When Naofumi first purchases him, Fohl is approximately twelve years old and already at level thirty-two, which is quite high for someone his age. He is noted to be of higher quality than other slaves. After further training and growth, he approaches adulthood around sixteen to seventeen years of age, and his looks become somewhat reminiscent of a young Aultcray Melromarc.

Fohl is a descendant of the royal family of Siltvelt, but he suffered persecution due to his mixed human and Hakuko heritage. His parents were lost in the war when he and Atla were young. To pay for his sister Atla's medical fees and cover their family debts, Fohl fought in the colosseum. Unable to manage the financial burden, he and Atla were eventually sold into slavery. The debt was cleared when they were presented to Naofumi.

Fohl is defined by his fierce overprotectiveness of his younger sister, Atla, bordering on an extreme brother complex. He feels he is the only one capable of protecting her and is initially reluctant to trust others. Although he appears hot-headed and rebellious, especially toward Naofumi, his true nature is more gentle and cautious than his fellow Hakuko, who tend to be battle-obsessed. He dislikes gratuitous violence and prefers peaceful solutions. After being corrected by Raphtalia regarding his overbearing attitude toward Atla, his humility begins to show, leading him to respect and follow Raphtalia, whom he calls Big Sis.

His primary motivation throughout the story is the protection and well-being of his sister. He initially feels jealous of Naofumi because Atla grows close to him, but he eventually recognizes and appreciates that the Shield Hero saved her life. Following Atla's death in the Phoenix battle, Fohl is wracked with guilt over his powerlessness. He resolves to protect the village and his comrades as she did, using her last wishes as his guide. This personal resolve enables him to become the chosen Hero of the Vassal Gauntlet, or the Seven Star Hero of the Small Hand.

Fohl specializes in unarmed close combat and was originally purchased by Naofumi as a physical fighter. His fighting style focuses on using his fists to break down defenses and damage opponents, with his advantage lying in the first blow. He has high willpower and stats, having been fighting long before he met Naofumi. Fohl trains in the Hengen Musou style, a legendary martial art that manipulates life force. His signature techniques include Tiger Break, where his chi expands and pierces through an opponent's body upon contact, releasing energy in the shape of a tiger, and Tiger Rush, a barrage of rapid punches. He later awakens his beast transformation, allowing him to take the form of a splendid and muscular white tiger, which greatly enhances his physical power.

His key relationships include his sister Atla, who is the center of his world and whose recovery, growth, and ultimate death drive his personal development. He has a complicated relationship with Naofumi Iwatani, starting with suspicion and jealousy but evolving into respect and camaraderie, with Fohl eventually calling him Aniki or Big Bro. Raphtalia becomes a figure of admiration and leadership for him, acting as an older sister who corrects his misconceptions. Jaralis, a lion demi-human who killed his father, serves as a primary antagonist in the Siltvelt arc, whose defeat prompts Fohl's transformation and resolve. Fohl begins his journey as a jealous, overprotective brother but matures into a reliable warrior and leader who cares deeply for his companions, treating them with the same affection he once reserved only for Atla.