The game begins with an in-game cutscene showcasing the party of main characters around a campfire backdropped by the wreckage of Zanarkand. As the camera work focuses on Tidus while he ascends a small hill and looks over the ruins, it is accompanied by the game's opening line, spoken by Tidus: "Listen to my story."

The suggestion that Final Fantasy X is Tidus' story is enforced by Tidus' first-person narration throughout much of the game, and is mentioned at various points in the game's dialogue. Tidus then recounts how events have lead to the present. At the beginning of his role in the story, Tidus, an inhabitant of Zanarkand, is preparing to play blitzball in the Jecht Memorial Cup — a tournament in honor of his lost father, Jecht. Ten years prior to the events of the game, Jecht mysteriously disappeared while on a blitzball training expedition out at sea. A successful blitzball player, Tidus felt the pressure to match, if not surpass, his father's skill. Tidus holds animosity toward Jecht for this and other reasons, including the fact that his mother would ignore Tidus in favor of giving attention to Jecht and because his disappearance led to his mother giving up the will to live.

During the tournament, Zanarkand is attacked by an immense creature shrouded in water. The city is destroyed in its path, and Tidus manages to escape a similar fate before the blitzball stadium collapses. While the destruction goes on, Tidus spots Auron, an old friend of Jecht and mentor to Tidus. Auron claims he has been waiting for Tidus, and reveals that the creature is called "Sin." Auron and Tidus fight their way towards Sin, much to Tidus' confusion. Once there, Auron drags Tidus into the depths of Sin, claiming his story begins here.

Tidus awakens to find himself in the world of Spira, where he quickly runs into the eccentric salvager race, the Al Bhed, and learns from a young Al Bhed girl named "Rikku" that 1000 years have passed since the destruction of Zanarkand. After another attack by Sin — who Rikku says has been a plague on humanity ever since Zanarkand fell — Tidus arrives at Besaid Island. It is here that he meets Yuna - a summoner who plans to embark on a pilgrimage to bring about the destruction of Sin. Along with her guardians Lulu, Wakka and Kimahri, Tidus navigates his way throughout Spira in the hope of finding his way home. Along the way, Tidus reunites with Auron, and even Rikku also joins the party as a guardian.

Throughout the game, Tidus slowly matures, changing from a somewhat naive and self-centered youth into a selfless hero. This transformation is also hinted — through several flashback sequences — to have occurred in Jecht himself, who Auron reveals to have taken part in a similar journey ten years earlier. Auron further reveals to Tidus that Yuna's father, Lord Braska, Jecht and himself achieved with that journey the very goal that Yuna was currently seeking in her mission. However, Sin returns every time it is destroyed, and Auron reveals — much to Tidus' horror and confusion — that Jecht himself has returned as Sin.

As the game progresses, Tidus learns more about Spira and the concept of the summoner's pilgrimage, but the answers to some of his questions — particularly why his father has become Sin, why Sin returns each time it is destroyed and why Zanarkand was supposedly destroyed 1,000 years in the past when Tidus remembered it being attacked only a short time before — elude him for some time. He also begins falling in love with Yuna — despite a warning from Lulu that he should not allow himself to — and shifts more toward Yuna's way of thinking (that the sacrifice of oneself is worth the happiness that destroying Sin would bring to people). For her own part, Yuna begins to approach situations in a manner more similar to Tidus (questioning everything rather than accepting it at face value). Tidus also begins relinquishing the hatred he long held for his father, and, in time, learns the answers to all of his questions, much to his dismay.

In truth, if one summons the Final Aeon (the goal of the summoners' pilgrimage), it will destroy Sin - but the process will result in the summoners' own death. Summoners have to sacrifice their lives to bring peace to the world (a short period of time known as "the Calm") only for Sin to return ten years later. Furthermore, the fayth of the Final Aeon is someone the summoner is personally close to, forming a powerful link between summoner and aeon that grants them the strength to defeat Sin. However, Yu Yevon, the spirit inside Sin, rises from the ruined remains of the creature and possesses the aeon which defeated Sin, slowly transforming it into a new Sin. It was this fate which claimed Tidus' father, Jecht. Despite the maturity he gained along his journey and his willingness to sacrifice himself to aid Braska in bringing the Calm to Spira's people, he was rewarded only with the additional cost of being forced to bring chaos as the new incarnation of Sin.

As the party approaches Zanarkand, another disquieting fact is revealed: neither Tidus nor Jecht are actually ordinary human beings. They, and the Zanarkand they hail from, are dreams of the fayth, the same as the aeons. Their city, Dream Zanarkand, was created 1,000 years earlier at the same time as the destruction of the original Zanarkand. There had been a war between Zanarkand and the city of Bevelle, a war which Zanarkand could not hope to win. As a result, Yevon, Zanarkand's leader, sought to preserve his city's memory, even if he could not save the original.

Thus, he had his city's surviving people become fayth on nearby Mt. Gagazet, and he then used their memories of Zanarkand to create a new city in its image, far removed from the Spiran mainland and war. Additionally, he created Sin by drawing on millions of pyreflies and coalescing them around his body. His intention was that Sin would serve to protect him and the fayth while he summoned Dream Zanarkand, and that it would also provide a means to destroy machina (machines) and prevent anyone on the mainland from discovering Dream Zanarkand. While Sin performed this function — and its instruction to attack any large settlements of people, in the further hopes that the populace of the mainland would be too pre-occupied with Sin to consider journeying far out to sea — as instructed, Yevon, for his part, would become known as "Yu Yevon" ("the Curse of Yevon") and lose his own humanity, becoming nothing more than a disembodied spirit that existed with only the desire to maintain Dream Zanarkand's existence.

The fayth of the aeon Bahamut reveals to Tidus that they would like him to find a means to permanently defeat Sin, so that they can all finally rest. However, the fayth also reveals to him that if he does that, the summoning of Dream Zanarkand and all its people — including Tidus himself — will disappear. When the party reaches the ruins of the original Zanarkand, they are presented with yet another startling revelation by the unsent form of Lady Yunalesca, the Yevon religion's figurehead: aside from the Final Summoning, there is no other known method of defeating Sin. Yuna, however, is unwilling to sacrifice any of her guardians, and refuses to accept the Final Summoning.

Yunalesca becomes dismayed at Yuna's defiance of the rites of the summoner's pilgrimage and attempts to kill her and her guardians. A fierce battle ensues, Yunalesca is defeated and her spirit abandons the Zanarkand ruins. Without Yunalesca, the Final Aeon can never again be attained, leaving Yuna and her companions with only the option of truly finding an alternative method of vanquishing Sin, one that will not allow the creature to return.

To achieve this, they attempt a straightforward assault on Sin, cracking open its shell and invading the interior of its body. Eventually, they find Jecht and Tidus is reunited with his estranged father. Their reunion is cut short, however, for Jecht reveals that Tidus and his companions must fight and defeat him in order to bring an end to Sin and Yu Yevon. Once defeated, he urges Yuna to summon her remaining aeons and use them to weaken Yu Yevon, leaving him vulnerable for the first time in 1,000 years. After she does so, Tidus reveals to his companions — including the young woman he has fallen in love with — that once Yu Yevon falls, his own life will be forfeit. Confused but determined, the party engages Yu Yevon in a final battle and destroys him, ridding the world of Sin permanently, as well as allowing the fayth to depart and the summoning of Dream Zanarkand to end. Tidus himself then begins to vanish, and after offering Yuna a painful farewell, he dives off the airship Fahrenheit into the clouds below, where the awaiting spirits of Braska, Auron (also revealed to be an unsent) and Jecht welcome him to the Farplane.

Tidus figures prominently into the plot of Final Fantasy X-2, though his appearances in the sequel are few. Also, because players have the option of renaming Tidus in Final Fantasy X, he is exclusively referred to with pronouns ("he" and "him") just like in the first game, and Rikku calls him "you-know-who" in Final Fantasy X-2. Two years after the events of Final Fantasy X end, Rikku shows Yuna a sphere found by Kimahri on Mt. Gagazet displaying a young man who looks like Tidus trapped in a prison. This compels Yuna to join the Gullwings, a sphere-hunting group, and travel around Spira in the hopes of finding more clues that Tidus may be alive. The individual seen in the sphere is eventually revealed to be Shuyin instead, but if the player presses the "X" button during the final scene in the Farplane, the player will be rewarded with an extra scene that features Tidus being revived by the fayth in gratitude of Yuna saving the world a second time. He is then reunited with her (the "swimming upwards" clip from the ending of the previous game is shown, and it is shown that he has been returned to Besaid) and allowed to live out a natural lifespan, so long as the Fayth can maintain it. In the ending, Yuna also begins narrating the events of the game to Tidus. If the player can manage to complete the game with 100% completion rate (doing not only the main storyline missions, but many other optional tasks), there is another final scene with Tidus and Yuna, at the Zanarkand ruins, in which he reveals the nature of his return.

The game's scenario writer, Kazushige Nojima, has expressed the relationship between the player and the main character in a Final Fantasy title is always something he's concerned with, and when penning Final Fantasy X, he wanted to try something new. He wanted to attempt establishing a connection between the player and character such that—since both are finding themselves in a new world—the player's progress through that world and growing knowledge about it would be reflected in Tidus' own ever-developing understanding, a connection allowed to the player through Tidus' first-person narration of most of Final Fantasy X, in which the player advances that narration. Nojima created a brief description for Tidus to give the character designer, Tetsuya Nomura, a rough scenario to work with. Nomura used the description to create a sketch to get input from Nojima and other staff members.

Nomura has expressed after designing serious and moody main characters for Final Fantasy VII and Final Fantasy VIII, he wanted to give Tidus a cheerful attitude and appearance, which is reflected in the name Kazushige Nojima chose for him (Tidaa is the Okinawan word for "Sun"). He's also explained he wanted his clothing and accessories to suggest a relationship with the sea. For example, his outfit bears a distinctive blue theme, and the symbol of Tidus' Blitzball team on his clothing is designed after a fishing hook. The symbol is designed as an amalgamation of the letters "J" and "T" (the first letters of Tidus' name and that of his father, Jecht).

Nomura has also mentioned a contrast between the lead male and female protagonists was established by Yuna's name meaning "night" in Okinawan. This contrast is also represented with the items required to empower their Celestial Weapons; the Sun Sigil and the Sun Crest for Tidus', and the Moon Sigil and Moon Crest for Yuna's. Due to the player having the option to change his default name, Tidus is never directly referred to by name during audible dialogue. The only in-game appearance of his name is on a name plate on an Auroch locker in the Luca stadium as "Tidu", written in the fictional script used in Spira. Because his name is never spoken out loud in Final Fantasy X, its intended pronunciation has been a subject of debate among fans. Interviews with James Arnold Taylor, Tidus' English voice actor, and spoken dialogue from the English version of Kingdom Hearts—which featured the character in a cameo—portray it as "tee-dus" whereas one instance in the English version of Kingdom Hearts 2 exists in which the character's name is uttered "tie-dus".

Tidus has also appeared in games outside of the Final Fantasy X continuity. A more youthful version of Tidus on the Destiny Islands as friends of Sora and Riku appear in Kingdom Hearts series. In the first Kingdom Hearts, he appears with younger versions of Wakka and Final Fantasy VIII's Selphie Tilmitt, serving as an optional sparring opponent. He also makes a cameo alongside Wakka and Selphie in Kingdom Hearts: Chain of Memories. In Kingdom Hearts II, he does not actually appear within the storyline, but is briefly mentioned by Selphie. Tidus appears in Itadaki Street Special along with Auron and Yuna.

In Dissidia: Final Fantasy, Tidus joins in helping Cosmos though he has his own agenda to find Jecht and defeat him out of grudge and for his father's sake.
Though based on Amano's design, Tidus' alternate costume has the bright color scheme that Nomura designed for him.

Tidus has received an overall positive reception, and has also had various types of merchandise modeled after his likeness; for example, action figures and jewelry. GameSpot commented players might not initially like the character, but would eventually find him "suitably endearing." They stated that he had the "surprising depth" characterized by past Final Fantasy protagonists, and called the ending involving Tidus "emotionally charged and satisfying". Eurogamer stated that Tidus and the other characters "make much more dignified and believable decisions than those made by their predecessors in other Final Fantasy games." The relationship between Tidus and Yuna was listed by GameSpot as one of the "Great Loves" in video games. It referred to their relationship as "one of the best (and ultimately saddest) examples" of a mature romance in games and cited the progression of the romance throughout the story as one of the game's best elements. GameSpot called the story revolving around their relationship "interesting" and "tender".

Tidus was also compared to Squall Leonhart from Final Fantasy VIII. IGN noted the differences in appearances between the two protagonists, citing Squall's darker colored outfit and "permanent mope" and Tidus' brighter outfit and weapon along with "an indelible grin". Because of his English-language voice work, GameSpot commented it would have preferred "an almost-mute lead character, a la Squall from Final Fantasy VIII." Regarding the character's English-language voice work, IGN stated the character "has a tendency to speak a little too high and a little too fast when he gets excited." GameSpot referred to Tidus as "annoyingly whiny", and Eurogamer echoed similar statements by referring to his voice acting as "whiny" and "detestable". 1UP.com listed him as the worst dressed video game character, citing a "deal with it" outfit design by Nomura. They further commented that despite the "preposterous" design, Square was able to "successfully sell" Tidus as Final Fantasy X's main protagonist.[26] James Arnold Taylor has also commented on his voicework for the character, stating that it did not seem realistic to him to have Tidus react in any other way than to truthfully show his emotions. While he also said there were things he would change about his performance if he could do it over again, Taylor said he loved voicing Tidus and thanked fans of the game for complimenting him on his work.