Rex

"We are the Shadow Garden. Or was it the Shadow Guardian? Oh, whatever. I’m Rex. Rex, the Game of Betrayal."

- Rex

Rex (レックス) was a Named First Child of the Cult of Diablos, titled Game of Betrayal (叛逆はんぎゃく 遊戯ゆぎ). During the attack on Midgar Royal Spellsword Academy, he was tasked by Sir Gaunt to retrieve the Eye of Avarice artifact control unit from Sherry but was thwarted and killed by Shadow.

Appearance
Rex had the appearance of a 'flippant man' with dull red hair and have the eyes of a starving feral dog.

During the Cult's siege on Midgar Academy, he wore an imitation of the Shadow Garden uniform which included a jet-black coat and a mask.

In the anime, Rex is seen in a black uniform with a red vest, black boots, and carries two large swords on his waist without wearing a mask.

Personality
"Difference in our strengths…… Do you really think you’re stronger than me?"

- Rex ferociously scowls at Glen

Rex was a vicious, arrogant and capricious man who treated everything as a game regardless of how serious the situation is. He liked to humiliate those who he believed were below him, but he was good at provoking his opponents in order to take advantage of their exposed points and weaknesses to do so.

Like many members of the Cult, Rex was overconfident. He was convinced that he was invincible and severely overestimated his abilities.

Rex never felt fear until he sweat in terror for the first time in his life, when he saw all of his men being eliminated by a single student.

Midgar Academy Terrorist Attack
Rex arrived at Midgar Kingdom and joined Lutheran Barnett to commit misdeeds throughout the capital, while claiming to be from the Shadow Garden, with their purpose to lure them out. When he heard the lost contact report of his men, he ask his superiors what's the next step, which he replied that its fine because he located the item he need which is their priority to retrieving the item.

Rex and the cult forces under Lutheran infiltrate and took over the Midgar Academy. While his fellow Children rounded up the students and killed anyone that opposed them, Rex headed to Sherry Barnett's study room to retrieve the Eye of Avarice's control unit. He found Sherry and was about to kill her when two Crimson Order knights intervened. Sherry escaped, while Rex defeated the knights.

Rex met up with Lutheran and informed him of what transpired, which upset him and he told Rex to quit playing around. Before Rex and his men immediately went out to search for the artifact, he informed Lutheran that several of his men had been killed, which Lutheran suggest that Shadow Garden have taken the bait. Rex then warned Lutheran to be careful. While walking through the school's premise, he watched as his men are being taken out by a student, much to Rex's shock.

Rex fought back against the interloper only to be overwhelmed by his incredible power. Rex wrongly deduced that the student might be using an artifact, having noticed wounds on the boy, also believed that he might be reaching his limit. He taunted the student hoping to get him to lose his composure. When it worked, Rex prepared himself only to be launched through a wall and crashed into a classroom.

Rex laughed, thinking he had won only to look around and find the corpses of multiple Children. Upon realizing that all these Children were killed by that student, Rex sweat in terror for the first time in his life. He only had a brief moment to muse about that boy's unlimited strength before said boy entered the room and eviscerated him.

Powers & Abilities
Rex was one of the strongest of the Named "First Children" who have provided extraordinary contributions to the Cult. Rex possessed stronger physical strength and magical powers compared to the average knight. Because of his strength he was promoted to a First Named Child

Physical Prowess
Rex was an excellent magic swordsman being able to best both magicless Glen and Marco Granger in a fight. However, he (like everyone else in the Cult) was too weak against Shadow.

Magic
Rex was capable of using magic as he intensifying his vision to its limit and focusing his gaze, which he can detect any rapid movements.

He is also able to channel all his magic into protecting his internal organs.

In the anime, he cast a net around himself that stretches using his magical power like a ball by linking both ends of his swords together to act as a barrier which detects anything as soon as it passes through.However, Cid broke through it easily, to Rex's surprise.

Battle Estimation Deduction
The reason Rex called himself the Game of Betrayal is because he can completely expose his victims with minimal information and used it to his advantage. His combat experience and sharp mind enables him to identify his opponents' weakness and attack them psychologically with taunts.

Cult of Diablos
He was one of the Cult's Named First Children, a strong group used as an assaulting force when needed. Being a First Child, he has command over other members of the Cult.

Lutheran Barnett / Sir Gaunt
His superior. Their relationship was tense due to how little respect Rex showed to him. The former Rounds Knight was patient with Rex's attitude until he reported what happen with the Eye of Avarice to which he was enraged and had threaten him to retrieve it from Sherry. When Rex didn't come back, the former Rounds Knight called him useless, unaware that Rex was killed by Shadow.

Sherry Barnett
His primary target during the raid on the Academy. Rex's cocky attitude became his undoing when he allowed the Researcher to escape where she later met up with Cid.

Glen
His opponent. Upon arriving to retrieve the Eye of Avarice from Sherry, Glen protected her from Rex's onslaught stating that his skills alone are enough to match against his magic abilities. Feeling insulted, Rex was confident in killing the Knight and so he did with ease.

Marco Granger
One of his opponent. The Knight's incapacitated body was seen in the same room where Glen was killed.

Shadow
Although Rex was unable to identify the student as the Shadow Garden's leader, he was able to notice that he's too injured to keep fighting when he saw his blood stained uniform and thinks he used an artifact that boosts his abilities where he wrongly concluded that the student has no chances of defeating him. That is until Rex witnessed multiple corpses of his subordinates before being killed by Shadow after being complimented by him.