A few years after the Order of Mata Nui was founded, they discovered a single unique Matoran of a new element they dubbed 'Peace'. This Matoran of Peace, Nomi, was recruited into the Order and began training with Helryx. She was later transformed into a Toa and added to the Toa Artakha.

Years later, the Toa Artakha came to Mata Nui's aid during the Dimensional Relocation of Luna Magna, an incident started by Karzahni that caused a dimensional rift to be opened in space, which pulled the planet Luna Magna and thousands of powerful artifacts into the main BIONICLE Universe. Unfortunately, Nomi died during the incident after releasing a Nova Blast.

After Nomi's tragic death, the Order of Mata Nui found another Matoran of Peace, Haku, and transformed him into a Toa as well, hoping to train him as their greatest weapon. However, Haku died in a battle not too long after. This process repeated itself with Ko, the third Matoran of Peace, who was killed when the Order of Mata Nui attempted to recapture Flandrex.

Each Matoran was discovered consecutively only after their predecessors' demise, which greatly puzzled the Order. Eventually, the Order discovered Rei, the fourth Matoran of Peace, and brought her to Daxia.

The Order decided, due to the past history of the Matoran of Peace, that they'd keep Rei safe and hidden on Daxia without transforming her into a Toa, to prevent her from falling into the wrong hands.

Eventually, an incident would occur that would result in Rei being turned into a Toa.

Abilities & Tools

The Order of Mata Nui dubbed Rei's abilities the Element of Peace, but a better description of the power would be 'Barrier Manipulation.’ Referring to this ability as 'Peace' stuck, however.

The full extent of a Toa of Peace's abilities has never been defined, but studies done on Nomi and the other Toa of Peace discovered that they have control over anything that can be technically classified as a barrier, including Energy Barriers, Physical and Metaphysical Barriers, Spiritual, Magical, and Imaginary Barriers, and Quantum Barriers. 

Like all other members of the Order of Mata Nui, Rei's mind is shielded from mental attack.

Rei doesn’t carry any traditional Toa equipment or tools and would rather create weapons out of barrier energy. She typically fights with a simple sword and shield, though she has been known to throw sharpened spikes of barrier energy at her foes.

Rei wears a Kanohi Hau, the Great Mask of Shielding.

Personality

As a Matoran, Rei had a lazy, mischievous personality. She spent her time exploring the Order's headquarters and pulling pranks on her bodyguards, and she disobeyed Helryx's orders to cooperate repeatedly. However, she did not disrespect Helryx. She just wanted to have more fun while essentially trapped in the Order's headquarters.

After becoming a Toa, Rei matured greatly. She realized the extent of her power, and as a result, began having an intense urge to help with the Order's problems.

Trivia