On Metru Nui, Ahkmou was a skilled carver, but he was continually jealous of the accomplishments of Onewa, another carver. Shortly before the Great Cataclysm, Ahkmou discovered the long sought-after Po-Metru Great Disk. Nidhiki and Krekka somehow learned of this and recruited Ahkmou into a scheme to scam five other Matoran into giving them the remaining Great Disks. Ahkmou was stopped by the Toa Metru (including Onewa, who had become a Toa), and he reluctantly joined their cause to defeat the Morbuzakh.
At the time of the Great Cataclysm, Ahkmou was put into forced hibernation in a Matoran sphere along with the other Matoran of Metru Nui. Ahkmou was among the first six Matoran the Toa Metru rescued as they fled Metru Nui, but his pod was lost to the bottom of a river on the way from Metru Nui to Mata Nui. Makuta Teridax later found Ahkmou's sphere and awakened him. Although Ahkmou had permanently lost his memory, Makuta re-educated him about the Matoran's past life on Metru Nui and convinced him that his fellow Matoran were his enemies.
Makuta sent Ahkmou to live among the other Matoran on Mata Nui and do his bidding. Onewa (now a Turaga) allowed Ahkmou to work in Po-Koro as a trader despite being aware of Makuta's influence over him. Shortly after the Toa Mata arrived on Mata Nui to fight Makuta, Ahkmou sold infected Koli balls that spread a plague in Po-Koro. Takua and Pohatu thwarted this plan, forcing Ahkmou to disappear from Po-Koro for some time.
When Ahkmou later reappeared, the Turaga allowed him to return to his job as a trader, wanting to keep a close eye on him. Ahkmou eventually moved to Metru Nui with the other Matoran. When Makuta Teridax seized control of the Matoran universe, he made Ahkmou the "Turaga" of Metru Nui in recognition of his past service to him. Ahkmou used his position to put all of the Po-Matoran carvers to work making statues of Teridax. After Mata Nui defeated Teridax, Ahkmou moved to Spherus Magna to join the new society forming there, presumably avoiding people who were aware of his past.
Ahkmou was a skilled carver from Po-Metru. He had always been second best at everything he tried. When he found a Great Kanoka disk, he had a chance for revenge.
Ahkmou was friends with Ehrye; the two sometimes played kolhii [sic] together.
Ahkmou was a carver in Po-Metru. Ahkmou worked at a workplace apart from his home with other carvers. Ahkmou had his own carver desk where he kept his tools.
Ahkmou was a master carver, specializing in images of Rahi. His style of carving was very distinctive, making his statues easy to recognize. On Metru Nui, Hafu was one of Ahkmou's coworkers.
Onewa noted that Ahkmou seemed to be more worried about how many honors he would receive than how much work he finished. This was in contrast to Onewa, who himself took pride in his work.
Ahkmou used to climb up and down statues for fun.
On Metru Nui, Ahkmou was a builder and carver, very skilled at a number of things but not a master of any. He came in second to Onewa in everything his whole life, and this led to bitterness and resentment. His discovery of the Po-Metru Great Disk brought him to the attention of two villainous Dark Hunters. They persuaded him to lure five other Matoran into traps and to try to get the other five Great Disks. Ahkmou's plan failed due to the intervention of the Toa Metru. He disappeared shortly after the defeat of the Morbuzakh.
Ahkmou had not given up on his plans for revenge by the time tales of the Toa Hordika were being told.
Ahkmou was not punished for his actions on Metru Nui or Mata Nui.
Ahkmou was misguided. He was not brainwashed, but instead selfish and deceitful.