Al Bowen is a character who begins as an antagonist before becoming a crucial ally to the central group. He is the older of twin brothers, both of whom were born as test subjects of the Chapel Plan. This was a project devised to cultivate human beings with artificially enhanced intelligence starting from the fetal stage. Because of their exceptional genius, Al and his brother Jeff were unable to connect with ordinary children and were subjected to bullying. In an act of revenge for this mistreatment, the brothers created a deadly poison gas which they used to annihilate their classmates. When their parents discovered the truth of what they had done, the twins also killed them. After this event, with nowhere else to go, the two were taken in by the secret organization known as Egrigori. There, they joined other gifted children produced by the Chapel Plan and quickly rose to become leaders among them, developing various weapons and participating in research.

Al possesses a genius-level intellect, reportedly having an IQ of 200. His personality is marked by arrogance, a cheeky attitude, and an extreme reluctance to lose. He is deeply proud of his intelligence, often boasting about being the greatest mind in the universe. Initially, he shows a cruel side that contrasts with his youthful appearance, a remnant of his traumatic and violent past. After becoming an ally, however, this overt cruelty fades, leaving behind a haughty demeanor that is frequently corrected by his comrades.

Al's motivations are driven by betrayal and revenge. Egrigori, finding the Bowen brothers' methods too flashy and difficult to manage, decided to dispose of them after using them in an operation to capture the ARMS. An agent named Keith Red was dispatched to eliminate them. Keith Red killed Jeff, but Al was saved with the help of Takeshi Tomoe and was subsequently taken into the home of Ryo Takatsuki. Having been abandoned by the organization and lost his brother, Al proposes a cooperative alliance with the ARMS team. His primary goal is to get revenge on Egrigori for murdering his brother, and to this end, he provides the team with information and strategic support.

Within the story, Al's role often shifts to that of a strategist and explainer. He frequently uses his intellect to analyze situations and provide necessary exposition to help both the characters and the audience understand complex events. A key and recurring relationship in his development is with Hayato Shingu. Despite Al's pride in his own genius, Hayato often finds his behavior annoying and will respond by hitting him on the head. This physical form of tough love becomes a running dynamic between them and a method of correcting Al's attitude.

Al undergoes significant development throughout the narrative. He starts as a self-centered individual who only trusts his own intellect and holds a general disdain for others. Through his interactions and shared struggle against Egrigori, the ARMS members become a new family for him. He gradually learns to trust and care about other people, moving beyond his purely selfish motivations of revenge. His reliance on his brain is challenged, for instance when he confidently challenges Dr. Samuel Tillinghurst to a game of chess, only to suffer the humiliation of losing a perfect eight games out of eight.

As for his abilities, Al is a technological and scientific prodigy. He is a skilled hacker and proficient in operating machinery. In combat, he and his brother utilized remotely controlled cyborg dolls named Plus and Minus, which were created from the bodies of deceased soldiers. These cyborgs served as their primary means of engaging enemies directly. Al is also notably a quick learner; after being subjected to being hit on the head by Hayato, he later adopts the same gesture himself, using it on stubborn individuals he encounters, indicating he has internalized this form of discipline.