Mateus wears light, golden colored armor with purple robes underneath it. His hair is blond and spiked, with an extra-long ponytail. On his chestplate are black and white stripes tracing his ribs, and on his waist and back are demonic looking faces. His gauntlets sport extended claws. Mateus also wears purple make up on his eyes and lips. He also seems to wear a purple crown. Being the ruler of Palamecia, the Emperor is arrogant, but also is very intelligent and manipulative, like when it is thought that he kidnapped Hilda as a prize, but it was a setup to trap the heroes instead. Another case is when he almost tricked the spirits of Minwu, Josef, Scott, and Ricard, asking for their forgiveness and offering them eternal life. Despite his arrogance, he is often polite when referring to his enemies by name or calling them gentlemen but at the same time he is quick to call them insects or worms. He also seemed to be a misanthrope, harboring a hatred of Humanity. This is especially evident just before the final battle against the heroes in his Hell Emperor form, as well as being defeated in his Heaven Emperor form, declaring humanity to have a flawed sense of justice and forsaken love, and being inherently violent.
In Dissidia Final Fantasy, he retains his personality from Final Fantasy II and some more is added. The Emperor is always calm and never seems to lose control of his emotions, he never seems to get worried because he believes that his plan will succeed without fail. His intelligence is also again demonstrated, as it is he who formulates the plan to kill Cosmos for good and end the war in Chaos' favor using the Crystals. This is also another example of when he tricks the heroes, as it is their quest for the Crystals that lets Chaos destroy Cosmos and nearly erase the heroes, as well as his own comrades.
