Legend of the Ultimate Sword

(also known as LOTUS, 最終剣の伝説 or Saishuuken no Densetsu) Legend of the Ultimate Sword (abbreviated LOTUS) is a Verse of Pharon occupying a position opposite Mirron's Muverse, and is the founding narrative of the entire Sinon continuity. It tells the story of a higher-dimensional being named Zan, who is dragged down into normal space and forced to inhabit a sword. This "Zanhoshi" is then used to power a device intended to make all times and places available for viewing, which fractures reality and leaves the universe in a multiverse state. This event is called the Mazzaroth Disaster, named for the viewing device. Each disparate timeline has its own Zanhoshi, and bringing these separated Zanhoshis to the same place in different timelines causes the timelines and swords to begin to merge. A completed merging results in a new timeline, with its own retroactive continuity, as well as a single, new Zanhoshi. Eventually, all Zanhoshis must be reunited in order to make reality whole again, and send Zan back to its home dimension.

The difference between one Verse and another is usually at the fundamental, natural level (such as differing laws of physics), with other minor differences being the result of the initial major one(s). However, the breakup of reality is not that simple. Zanhoshis are bound to the fabric of spacetime, and what happens to them is reflected in the underpinnings of whatever Verse they're in at the time. There can be multiple timelines within each Verse, distinguished only by different causal results or individual choices. When Zanhoshis undergo unusual events (such as breaking, reforging, etc), Verses tend to remain as they are, with the only changes occurring at the timeline level within a Verse.

Primeverse
Primeverse is the original Universe - a truly unified, singular timeline. Because it is doomed to be broken by the eventual descent of Zan, even Primeverse is marked by Zan's retroactive influence. It is this very influence which leads to the Zanhoshi Advent, creating a bootstrap paradox.

In Primeverse, Taliro has an older brother named Alroit who is also injured in his training accident. Alroit's prostheses are far more extensive, making it impossible for him to have children. To satisfy Valore codes of honor, Taliro fathers a child by Alroit's wife, to give them an heir. Thus Drake is born, half-brother to the Zet and possessed of a greater share of Zan's influence than his later siblings. Drake is responsible for the creation of Zanhoshi Prime, and because of this causal link he cannot be erased from history. Thus, when Alphaverse is created and Alroit's existence is erased, Drake remains. This is the cause of much confusion for the Zet as to his origins.

When the Mazzaroth device is first activated, Primeverse ceases to exist, and the other Verses of LOTUS are created. Each Verse has its own retconned history leading up to the activation of the Mazzaroth, and none of them are exactly identical to the events of Primeverse. As a result, the actual Primeverse sequence of events is not seen in the LOTUS narrative - only the retconned versions from other Verses, which leads many characters to erroneous interpretations of the Mazzaroth Disaster for much of the story.

Alphaverse
Alphaverse is the composite timeline followed by the main narrative, formed by continual Zanhoshi Fusions, and as such is constantly in a state of causal flux. Retrospectively, it is the one timeline that remains as a result of all other timelines and Verses merging.

In Alphaverse, Mezzo is responsible for the creation of Excalibur, the Alphaverse version of Zanhoshi Prime. When Excalibur is activated by Zetoshin, it causes the Zanhoshi Advent, and Drake appears. Drake volunteers for the first manned space probe mission, and is lost to the Zanhoshi Anomaly. Excalibur is then used to power the Mazzaroth, with the intent of locating both Taliro and Drake. The resulting energy release razes the Valore capital city, killing everyone on the planet except the Zet, who are rendered immortal by contact with their Omegas.

Trivia

 * LOTUS is the best Verse in Sinon, because it has Mezzo in it.