Alan is a former soldier of Lestava and a co-founder of the now-defunct Cross Guard, later becoming a key member of Team MÄR. He is a hardened, smoking warrior whose power is considered to be at the Knight class level. Physically, Alan is a man with tan skin, dark eyes, and brown hair with lighter highlights on his bangs, and he bears a pair of scars on the right side of his face. His reputation as an almost unbeatable fighter is well-known, yet he has an unusual allergy to cats, a weakness that manifested as a result of having shared a body with the dog Edward for an extended period.

Alan's personality is defined by a serious and often overconfident demeanor, though this rarely proves to be a flaw due to his immense power. Beneath this tough exterior, he carries a deep well of emotional trauma stemming from his childhood friendship with a boy named Pump. In their youth, Alan, who was the toughest kid in his hometown, befriended the mistreated and weak Pump, often coming to his rescue. In an attempt to help Pump gain courage, Alan introduced him to a fire ÄRM he had been secretly training with. However, Pump stole the ÄRM, used it to destroy a pack of two-headed dogs, and became intoxicated by the feeling of power, accusing Alan of hypocrisy before running away. Alan has always blamed himself for unintentionally awakening a lust for power in Pump, who eventually became the evil and dreaded Chess Piece known as Halloween. This trauma resurfaces powerfully when Alan is deeply shaken upon learning Halloween's true identity, a moment that causes him to relive his past failure.

Alan's primary motivation throughout the story is to atone for his past mistakes and protect others from similar fates. He shows great concern for the well-being of his allies and innocent people, once willingly taking the brunt of an attack meant for spectators. His role in the overarching narrative is that of a mentor and a legendary hero from the previous war against the Chess Pieces. It was Alan who, using the Dimension ÄRM Gatekeeper Clown, summoned Danna Toramizu from Earth to MÄR-Heaven to fight in the first great war. He took Danna into the Training Gate to prepare him and eventually appointed Danna as the leader of the Cross Guard, with himself as the second-in-command. During that first war, Alan fought Halloween to a draw, but a curse from Halloween's Darkness ÄRM sealed Alan inside the body of Edward, the court guardian and custodian of Princess Snow. For six years, he remained trapped, transforming back into Alan only when Edward slept three times, and reverting to Edward upon falling asleep himself.

Key relationships heavily influence Alan's journey. His tragic history with Pump, who became Halloween, is the central emotional conflict of his character. He also shares a strong bond with Princess Snow, having sensed the danger posed by the queen, Diana, and fleeing the castle with her while still inside Edward's body. Alan is a mentor figure to Ginta Toramizu, the new other-worlder, and to the young Alviss, whom he once stopped from committing suicide after Alviss was cursed by Phantom, insisting that the boy train to become stronger and decide his own fate. His connection with the dog Edward is unique; after being separated into two distinct beings by Ginta, Alan gains his full human form again, though his allergy to cats remains as a lingering side effect of the fusion. Later, he develops a close relationship with the cat-like Chess Piece Chaton, eventually living with her after the war's conclusion.

Alan undergoes significant development, primarily through finding closure for his past trauma. His final confrontation with Halloween, where he defeats his former friend, allows him to finally move beyond his guilt. His character evolves from a powerful but haunted warrior into a man who can finally live peacefully, as seen in the aftermath of the final battle when he is revived and lives alongside Chaton.

In terms of abilities, Alan is a formidable fighter who relies on a diverse collection of ÄRMs. His most frequently used weapon is the Air Hammer, a set of rings and bangles that are a Dimension ÄRM, allowing him to fire concussive blasts of air with an attack called Air Freeze to compensate for his lack of ranged attacks. He possesses the Flame Dragon, a Nature ÄRM that can conjure fire in any form, which he also uses to light his cigars. For training others, he uses the Training Gate, a Dimension ÄRM that slows time to one-sixtieth of its normal pace, though he cannot move while using it or enter the gate himself. He also wields the Guardian ÄRM Saint Anger, which manifests as giant armored fists from the heavens to deliver powerful blows. Other ÄRMs in his arsenal include Shadowman, which creates a copy of a person from their shadow, and the Guardian ÄRMs Merilo and Bumoru, who assist in his training gate.