Rex

Rex is the main protagonist of Xenoblade Chronicles 2 and a playable character in Future Redeemed. He is a salvager and the Driver of Pyra and later Mythra, the Aegis. His goal is to take them to Elysium to fulfill their dream and save Alrest from its fall.

Appearance and personality
Rex is a teenage boy with brown hair and yellow eyes. He wears a blue diving suit with brown and gold accents, mainly for use during his salvaging work. Not long through the game, an X-shaped segment of Pyra's Core Crystal appears on his chest. In Future Redeemed, Rex has a muscular build and his hair grew larger and now sports a small goatee. Rex wears a sleeveless vest with a collar similar to his younger year's salvaging suit, a skintight turtleneck, black pants with a tailcoat, and black boots. Rex lost his left eye in a battle and is now scarred.

Rex is enthusiastic, but inexperienced at anything outside his line of work, and rather naïve. He strives to protect and support his friends, often blaming himself whenever they are hurt or killed. However, he is careless from time to time, which puts him and his friends in danger.

Xenoblade Chronicles 2
The story opens with Rex salvaging out of the Cloud Sea of Alrest from aboard the small titan Azurda, whom he calls Gramps. Rex is worried about the titans dying out, which seems to be happening more often lately, and whether the fabled Elysium of the World Tree truly exists. The two go to the Argentum Trade Guild so Rex can sell what he salvaged. While there, he is unexpectedly summoned by, Chairman of the guild. Elite salvagers from Leftheria have been requested by a picky crew, and a huge sum of money is involved. There is some dissent amongst the rest of the crew over accepting Rex - he butts heads with Nia and has to defend himself from Malos, but they board the C.S.E.V. Maelstrom and move out.

The target ship is located, Rex and the other salvagers raise it, and the search begins. Jin decides Rex should join the search, so he does. The search crew finds doors blocked by what Jin calls "Addam's Crest", which will only open for a Leftherian, so Rex is ordered to open them. As he is therefore the first to enter, he is the first to reach the treasure inside: a woman sealed in a glass compartment in the wall. Intrigued, he sees a glowing green crystal on a sword stuck in the ground before him, and touches it despite Malos yelling at him not to. Jin instantly kills him and destroys the sword in an "act of mercy".

Rex wakes up in a grassy field, seeing the sealed woman standing beside a lone tree. Her name is Pyra, and she says they are in Elysium - or rather, a memory of it. She wishes to return to Elysium, and revives Rex using half her life force, making him her Driver. Part of the Core Crystal appears in Rex's chest, and the Aegis is recalled into his hand. He helps Pyra break free of Malos, and the two fight him off so the other salvagers can escape. Nia and her Blade Dromarch join Rex's side, and a mysterious black ship's arrival is countered by Azurda's appearance. Rex, Pyra, Nia, and Dromarch all escape on Azurda, but he is shot down and crashes on Gormott.

Torna ~ The Golden Country
Rex only appears at the ending of the game. As Pyra is shown resting on the Ancient Ship, a door opens with Rex behind it, referencing the scene in the beginning of the main game.

Xenoblade Chronicles 3
While not present within the narrative of Xenoblade Chronicles 3, a statue in his honor and representing House Cassini can be found in Memorial Hall in the City alongside the other five Founders.

A picture of Rex is later seen in the game's ending, where he stands over Pyra, Mythra, and Nia. All three women are seen holding babies, with him standing over them; it is heavily implied that he married all three of them, and that the babies are all his.

Future Redeemed
Rex, alongside Shulk, and Z are first seen confronting Alpha, telling Shulk that nothing will get through to Alpha as to him, he's a heartless machine. Alpha then unleashes a powerful attack, costing Rex his left eye.

Over a decade later, Rex shields Nikol from a Ferronis laser, much like Shulk saved Glimmer. After W's defeat, he inquires about who fed Moebius their location, Panacea points out Glimmer. Rex then scolds her for such irresponsible behavior. Shortly after, however, he expresses regret to Linka, who recognized Glimmer as well, and notes that Shulk faces a similar dilemma with Nikol, much to Rex's surprise.

Alongside Shulk, the other Liberator leader, he would guide the young squad of adventurers to, their home base.

Lore

 * Rex was brought to Leftheria as a young child, his parents presumably fleeing a war. The appearance of both Rex's mother and father implies them to be Ardainians. However, Rex is ethnically Leftherian, evidenced by the Ancient Vessel and the Spirit Crucible opening doors accessible only to Leftherians. Sadly, his mother would die shortly after delivering Rex to Fonsett safely, and his father would be found dead not far from the village.
 * Likely, his parents emigrated or descended from those who did, and fled back to the islands.
 * Further it is implied that Rex may be a descendant of Addam, being a native Leftherian, Mythra's second Driver, and similarities of the two both in appearance and demeanor. However, there is little to guarantee this.
 * Rex is a very outgoing and independent individual, shown to be capable of supporting himself as a salvager, but also supporting his adoptive family in Fonsett Village.
 * While he is 15 during the events of Xenoblade Chronicles 2, he states that he has been working as a salvager for several years prior to Bana contracting him for a salvage operation at Torna's behest.
 * A photo can be seen at the end of Xenoblade Chronicles 3 depicting Rex noticeably older than he was in Xenoblade 2, standing behind Pyra, Mythra, and Nia, all of whom are holding babies. The implication is then that he is the father of all three children.
 * Given that he directly identifies Glimmer as his daughter to Shulk and A in Future Redeemed, almost certainly this makes Pyra Glimmer's mother, as well would make him Mio's father by extension.
 * This would mean that three of the City's six Houses are descended from Rex; Vandham and Doyle being descendants of Mio, and Glimmer directly being the founder of House Rhodes.
 * Rex and Shulk would found the Liberators, a group dedicated to fighting Moebius and restoring their worlds back to order; the precursor to the Lost Numbers.
 * While Rex lost his eye against Alpha, historical records would attribute this injury to Moebius.
 * While in Aionios, Rex would care for Linka like a child of his own, between Rex being close to her parents, and both being among the few people to not be assimilated by Origin when the worlds Intersected.

As a boss

 * Stoutheart Rex (FR)
 * Stoutheart Rex (XC3)

Xenoblade Chronicles 2
As the main character of the game, Rex is the Driver playable for the longest time. He is the only Driver who can wield the Aegis Sword (not including in Torna ~ The Golden Country) and the Catalyst Scimitar. In chapter 7, can be called exclusively by Rex, making him especially strong in s. He also becomes the  in chapter 8, allowing him to use any Blade (except for any of 's Blades).

Xenoblade Chronicles 3
Rex is a Hero that can be added to the party after completing the mission The Two Saviors.

Future Redeemed
Rex is a playable character in Future Redeemed. His class is, an Attacker class focusing on critical hits.

Trivia

 * In Xenoblade Chronicles 3, Rex, Ino, Masha, and Shulk, are the only Heroes who will not assist the party in the final battle against Z, as they are all part of the Xenoblade Chronicles 3 Expansion Pass.