“Tao Duo” is the name given to the pair comprised by the Legendary Pokémon Reshiram (Reshiram) and Zekrom (Zekrom), who live in the region of Unova in the Mainline World. These two Pokémon are unique among their kind and revered in the region of Unova and others nearby as living deities. The two Pokémon are said to once upon a time have been part of a singular entity, the Drao or “Original Dragon”.

First records of the Tao Duo as individuals hail from early in the Previous Era, if not before, when humans attempted to extend their presence from the western part of the continent where Unova resides to the eastern one. In those early years, humans saw the confrontations Reshiram and Zekrom had against an entity known as Kyurem, who persistently tried to draw them away from the large pools of energy that constituted the Grass Archaic Safehaven (that would eras later become Emisre).

At some point in the far past, shortly before or during the Rain from the Heavens, Reshiram and Zekrom took notice of various colonies of dragons migrating towards the eastern side of the continent and followed them. As the Druddigon groups in those colonies managed to seize control of an abandoned Tower in what is now Unova, Reshiram and Zekrom eyed their behaviour in expectation that Kyurem could follow them and stir trouble.

At some point during the Rain from the Heavens, Reshiram and Zekrom joined to face Kyurem in final confrontation. While they emerged victorious and cast Kyurem into the depths of the Giant Chasm, they were left severely wounded and seek refuge in the Tower the Druddigon had inhabited. Druddigon, and the other Pokémon living near the Tower, took this as a divine intervention and worshipped the dragons, vowing to keep the Tower as a sanctuary for them. The two Tao Dragons morphed into stone balls and entered deep slumber so that they could recover.

Over the ~400 years that the dragons slept, dragons all around the continent got wind that they were established in the Tower and started making pilgrimages all around it. As the tower attracted more and more draconic attention, a civilization of dragons and other Pokémon slowly built around it, becoming the Dragonspiral Moors Sovereignty. Once Reshiram and Zekrom awakened it was renamed as the “Oohr y Drań Mahr-neeĥ”, or “Focus of the Dragons' Yearly-Circle”. Humans later gave this title a more lyrical interpretation as “Dragonspiral Tower”.

The civilization of the Vale grew around both dragons, who were recognized as bringers of Truth and Ideals. However, the Vale fell into civil war with the two factions trying to wrangle each one of the dragons into the fight. After a nasty incident that caused great damage to the Vale, Reshiram and Zekrom renounced the civilization as it crumbled and moved to the moors of Dragonspiral.

There, they morphed into stone balls again. Ashamed of the way they had been used during the War of the Vale and brought ruin to the kingdom, they left a portion of their power to their followers, and requested to not be woken up until the world could produce a “suitable hero”.

Reshiram and Zekrom would eventually raise once again at the tail end of N's campaign across the region, where the revolutionary leader attempted to address the two dragons in Dragonspiral Tower. It was Zekrom who woke up to the human's words and acknowledged him as a representative and together they quickly brought down the Elite Four. However, after it was shown that the entire campaign had been a charade orchestrated by Ghetsis, N and Zekrom retreated and disappeared for several days. Zekrom later returned to Dragonspiral Tower and met with his sibling there.

After that the two dragons resumed their places as de jure monarchs of the Sovereignty, though still mindful of their previous experiences they decided to stay within the realm and limit interaction with the outside world.

When the two dragons discovered that the reserves of food and tributes bad become scant during their absence, the two dragons became enraged that their acolytes had not kept maintenance of the tower. Still under the impression that N was a king with a people, they decided to go to him so that his vassals would gather from humans the tribute the Dragons felt was long overdue ( Tastes Anew ).

Being the only known trace of the first and foremost being created by the Dragon Trio, Reshiram and Zekrom have tremendous capabilities for (mostly) purely biological entities. They have a wide array of draconic techniques at their disposal and are proficient when fighting in close quarters, unlike other dragons of their tier such as Zygarde and Rayquaza.

Not counting the time they have spent morphballed, they are both among the longest lived biological beings in the Suocéverse, with an age that exceeds the 200 000 years. Due to the circumstances of their creation, they lack both biological sex and the ability of their bodies to gradually repair themselves like most other creatures can; instead they must rely on sheltering themselves under the cover of strong energetic pulses, or must morph into stone balls, to restore their bodies.

Both dragons are capable of sustained flight, being able to cover the entire ground of Unova in a single flight. They can take off and fly much like a modern jet plane, and can break the sound barrier (Tastes Anew).

• Tastes Anew (debut)