Alexander Macallan was voidborn in contrast to his brother and sister during the Macallan family's annual vacation. Of the children, he was the most unpredictable. He was a prankster at heart, annoying his siblings.
Despite his insubordinate attitude, he was favoured by his father the most. Sugihito was considered too weak to handle leadership roles and though Jingu was the most competent of the three, she was largely ignored.
After completing his training in the Imperial Guard Academy, Alexander joined the 4th Yokohaman Regiment. The Regiment was sent to the Eastern Fringe, near the borders of the Tau Empire. He was sent to fight a part of the Tyranid Hive Fleet Kraken on Drachma Prime. The Regiment was wiped out by the Tyranid forces and Alexander was listed MIA by Command.
It was a little known fact that he survived the disastrous campaign. A Tau Cadre from Fal'shia were fighting on Drachma Prime as well. The governor of the planet agreed to join the Tau Empire if the planet's defence by the Tau was successful. The Cadre was able to fight it's way to where the 4th Yokohaman last stood. He was rescued by a patrol of Firewarriors and defected to the Tau Empire as his Regiment was wiped out. Drachma Prime's campaign ended in a bittersweet note. The war lasted long and it was only until Tau Commander Shas'O' Shaserra took control of the Tau forces that it broke the long stalemate.
Alexander became a Gue'vesa, or Human Helper for the Tau. He joined the Water Caste's Diplomatic Corps for dialogues between the Tau and other Human nations, travelling frequently.
Alexander was active in the Octarius Sector during the Grand Republican Civil War. He was supposedly sent as an emissary representing Tau interests in Eagle Labs. He met the President of the Company, Blood Eagle on the use of a secret weapon on the war that was fought on the planet.
A retired Imperial Japanese Navy personnel turned mercenary Takanaga Okamura was sent to hunt and kill Alexander under the orders of General Headquarters. Hearing how Alexander was suspected to be Eagle Labs, he joined the raid in order to complete his mission. However in the Eagle Labs, Alexander was able to escape by exploiting various experiments carried out in the lab and his Firewarrior escorts.
Alexander was cornered to the sewers where he made his last-stand with the Exclusive Brotherhood, a local Genestealer Cult. He is believed to be killed in battle when Okamura shot him. His corpse was recovered by Okamura after the battle and was brought back to Tokyo for examination.
His corpse showed modification by the Tyranids when investigated, shocking the examining medics. His body was cremated with the ashes stored in an urn.
There has been conclifcting reports of varying credibility that he might have survived Octarius and the corpse recovered was a clone or double. If he is alive it is not known if he is a part of the Tyranid scheme to consume the Galaxy or working for some other power. It is advised for all nations to monitor their borders for his appearance and execute him when possible.