Fawful is Axem Blue's master, and partial creator in ARA. He uses his extreme intelligence, and alliance with Dimentio to try and for fill an ancient prophecy.
After Fawful had been defeated by Mario, Luigi, and Bowser, he had landed in Dimble Woods, while presumed to be dead. He soon recovered from his injuries, and went on to seek revenge against Mario, and Luigi. He had soon discovered Axem Blue's prototype form laying around in a junk heap, and decided to form his evil plan by building a killer machine out of him.
Midway through building Axem Blue, Fawful had trouble getting a big enough power source to power Axem Blue. He then stumbled upon Dimentio, who had recently escaped the Underwhere. They had made a deal together, agreeing to work with each other, as long as Dimentio gave Fawful a power source. The power source were two green crystal gems, created by Dimentio's magic.