Majaro was already much of a traitor before joining the False Emperor in his crusade. He was once a doctor at a high security hospital for the wounded from battles in space, however he had activaly experimented on these soldiers, sometimes even killing them if they were deemed failures. Once he was discovered, he was put through Tempora, a Coritan punishment where ones organs were placed in a machine body, and their feelings and emotion are disabled. It was a punishment to rid one of their identity and senses, and so Majaro was made into his current form. However, he didnt complain, he didnt yell out for Corellus. He felt pride in his new form. He made his punishment into a weapon and now he uses it with the False Emperor to improve his soldiers, or inflict as much pain as possible if they ever dare make a mistake.
Majaro in personaility is cold and caclating, putting science over anything else. Most Coritans deem him a freak and even the False Emperor questions his loyalty. Majaro will stop at nothing when it comes to completing his work, even if it means to remove ones body and soul.
His weapons are a bit weak, hes more backline and doesnt fight much. When needed, he will use paralyzing enyzemes that secrete from his metal shell in a gas to freeze enemies, then he just drags them to the back and does experimentation.