Akzer can be quite the trickster, just as any pirate is. In fact, he is so traitorous that he has Chronic Backstabbing Disorder (and is probably a Double Reverse Quadruple Agent). He was originally a Pirate Lord, but he gave up the lifestyle to become an apprentice of Caiaphus. He later betrayed them, allying himself with Sephiroth (who he probably was later going to betray anyway, had the character not disappeared into the Final Fantasy universe). When he was brought back to life by Tahar'ok, he joined him, but betrayed him later on as well. Akzer's time in the battle of the deceased saw him creating (and breaking) several alliances with the other dead characters. Once Set brought him back, he became a Pirate Lord once again, meaning that he was indirectly working with Uterio. Akzer is a typical pirate: he only allies himself with the most powerful to save his neck, just like his contemporary Keichi.
In the Beginning...
Akzer was the former lord of the Seven Metal Seas, meaning he was a pirate lord on the planet of Liquid-Metallicon. He was also an apprentice of Caiaphus, believed to be the second in command of the Order. He also seemed to know Sephiroth in a way, and had struck a deal with him: betray his master and get the AoC to become his new army, while helping Sephiroth get the Keruvim.
Akzer was a novice during the Apprentices' battle against Blackout, and vowed to bring the organization back, and the Makuta to his knees.
He had rescued Klak during a battle, and helped train him in one of Makuta Caiaphus's dangerous tests. Due to his defeat in this, Akzer then developed a grudge against the young Makuta, and transported away from the temple to his old ship, the Mazkertis, taking its power core. He used it to find Klak, but had a minor sidetrack: He transported to the Enterprise, and was imprisoned with the other crew members when Naju took over. He quickly used his wit to trick the Great Being into letting him go.
Akzer then teleported to where he found Klak, and attacked him. There, he revealed his secret plans to betray the AoC, and to use them as a crew to retake his pirate kingdom. The swashbuckling fellow fought as hard as he could, but since he was subject to the Makuta's anger, he was crushed into a can, and died.
However, a part of him survived. Naju, then a dying apparition, brought Akzer back to life, giving him his powers. Our pirate lord attempted to get Tahar'ok to kill Klak for him, but instead found himself becoming the servant of the Tahar'. Therefore, he went to the battlefield where his murderer had activated the Keruvim. However, a taste of a Great Beings power, and his betrayal instinct got Akzer killed by Tahar'ok himself.
Post Mortem once again
An unknown amount of time after Akzer's second death, Keichi was exploring a planet with Ravat, when an apparition of Akzer began to attack them. According to legend, this planet projects the memories of those in the area as certain enemies.
(the following was not covered in the game) This apparition disappeared once Keichi destroyed him.
Afterwards, Akzer was resurrected in the UG, and made an alliance with Tulio, the gelatinous being, Tidal Wave, and Rahn in order to escape the pocket dimension by fighting the other "undead" characters.
Somehow, he was brought back by Set to assist the Pirate Lords in fighting the Rebel Alliance (this is a game, after all). However, this time, Akzer's mutilated body had to be repaired with robot parts. To tell you how much of him was left after the can incident, Akzer speaks in a voice that is both robotic and slightly muffled. He was also immune to the vacuum of space, unlike most organic species in BZPB.
This version of Akzer didn't last long, as Klak once again destroyed him after a long fight... IN SPACE!
Post Mortem And Time Travel
Thousands of years later, F-Blackout brought Akzer back to life yet again, as part of a plan to use the Pirate Lords of Liquid-Metallicon to influence the past.
Abilities & Powers
Akzer is a master swordsman, and can open portals. He is also able to fill many beings' minds with illusions, as he did to Klak while the latter stayed in a virtual world. It is for this reason that most of the Pirate Lords respected him, and fear him to this very day.
The apparition of Akzer only has the attacks Keichi remembered him using. Whatever these are, we don't know.
Akzer's species are reptillian humanoids who grow a metallic exoskeleton (much like armor) at a certain age. This means when Klak killed him, his entire body was crushed within.