In the beginning, there was a group of humans. They were not regular humans though. They had wings and magic. These beings were named the following.

Fate. The Goddess of Fate.

Destiny. The Goddess of Destiny.

Path. The Goddess of every path and mother to Fate and Destiny.

Choice. The God of every choice ever made and father to Fate and Destiny.

Karma. The God that gives out both good and bad karma.

Time. The Goddess that controls time itself.

Vision. The Goddess that can see in the future, Mother to Time and Karma.

Retribution. The God that controls whether or not you need to pay for your sins. Father to Time and Karma.

Fear. The God of Fear.

Abyss. The God of the Abyss, also known as the Void (named it after his father.)

Void. The God that controls all empty spaced.

Panic. The Goddess that controls panic.

Beat. The God of music.

Tune. The Goddess of songs.

Melody. The Goddess of music and songs and mother to Beat and Tune.

Creativity. The God of all imagination that goes on.

Feelings. God of all feelings. Father to Merciful and Merciless.

Mercy. The Goddess of weather or not monsters get spared, Mother to Merciful and Merciless.

Merciful. The Goddess of giving out mercy.

Merciless. The God of rejecting mercy.

Souls. Goddess of all Soul Traits, Mother to Emotion and Glitch.

Virus. God of Viruses and Father to Emotion and Glitch.

Emotion. God of everyone's how someone feels.

Glitch. The Goddess of all glitches.

These gods lived happily in their own pocket dimension. But eventually, all the parents came to a conclusion. They would let their children create some multiverses as long as they didn't ruin the balance. The children agreed.

The Original Multiverse was created by the parents.

The second one was created by Fate and Destiny, also known as the Forced! Multiverse. Read the page for why.

Karma and Time created the third multiverse also known as WarVerse.

Abyss and Fear created the fourth also known as PeaceVerse.

Beat and Tune created a multiverse called BlindVerse.

Glitch and Emotion made a multiverse called TwistedVerse.

Merciful and Merciless created a Multiverse called MercyVerse.

As time went on the children took care of the multiverses. The parents dealt with the Original and new multiverses. The parents had formed a council to protect all multiverses and make sure nobody ruined the rules. But there was something different about Fate and Destiny's. They did not have a version of Error or Ink. Or anyone really. Just Undertale.

The council saw how Fate and Destiny's powers clashed. So they let Destiny create her own multiverse. At the start, the children never others multiverses. But as time passed, they watched the other multiverses. The council backed away as they saw the children get the hang of it.

A year later, Fate had an idea. She created a skeleton much like the original. She named him Ink. She whispered his job and the balance to him. Though Ink did not hear. He started to create without knowing the limit.

As the balance became more and more tipped, the council never noticed seeing as her parents were in charge of it and saw how she and her sister controlled it so well. But there was one person who did take notice. Destiny.

As the balance was almost tipped, Fate took a random sans and make him the Destroyer. Destiny felt bad for the skeleton now named Error. So she did all she could for him without being noticed. She leads him to a group of 'bad' Sanses and the Chara equals.

Fate grew to hate the skeleton due to her child hating him aswell. She snuck into some universes and did the same. All the other deities became confused as there was a new destroyer. Fate played along and acted confused. They never found out answers to how this happened and they couldn't change him back or redo what was done.

Over eons Destiny cared less and less on whether or not she was discovered breaking the rules. Nobody knows what happened next or to the other multiverses. Or even to the council. That's as far as we know of that MegaVerse. But of course, there are more. The one they live in is SecondaryVerse. The original Mehaverse is called PrimaryVerse. There are more such as ResetVerse and ProdigyVerse.