Shortcut:
this blog post that explains this Majora's history and present in a much more succinct manner, and
this one that contains headcanons for it.
Below text was typed up yeeeears ago for my tumblr (wrathfulmajora) and it's pretty cringe (you've been warned).
Evil never DIES.
When Majora was defeated, it left the mask. The evil entity found itself in another realm where it stayed for a while to lick its wounds, and it eventually founded a cult following devoted to itself amongst the new realms natives. A rag-tag band of Twili that reminded it ever-so MUCH of the tribe to which it owed its very existence that, once it had sucked them dry of every last ounce of energy they would offer to it WILLINGLY, it consumed them out of ancient spite.
Desiring more, desiring revenge, Majora wrested itself from the piddly little Realm it had been knocked into, climbing - scrabbling - CLAWING its way back into the land of Termina. No longer bound to the confines of the mask it had been sealed in, the demon was FREE.
However, it’s powers were still too…
WEAK.
It couldn’t call down the moon like it had been able to once upon a time.
It couldn’t rain ruin and destruction down upon the poor souls of the land.
Not yet.
The people of Termina had never really KNOWN what had transpired. All they had known was the Skull Kid and the Moon.
They had never seen any of its forms. They knew it by MASK only. Its name had been forgotten with time.
Majora quite liked having a CULT, for the short time that it had had one.
So that’s what it did. As before, the demon set out.
It silenced the Great Fairy, first of all, for she would KNOW.
Then it promised people POWER. All they needed to do was revere it.
Worship it.
Look upon it as a GOD.
Not all of them did, of course. That was only to be expected. Within weeks, however, Majora had a new cult; small in number, but growing. Terminans: Humans, Deku, Gorons, Zora. The CORRUPT, the power-hungry, THE FOOLISH.
It was worlds different from being a mere TOOL.
Majora FELT like a GOD.
Perhaps it wouldn’t kill them. Not for a while.
Several generations, perhaps.
It was too fun to keep them all alive and stupid.
This Majora uses the non-canon manga story wherein Majora was originally a dragon.
Default is post-verse non-canon "Majora was knocked out of its mask and into a different realm upon its defeat. While it has managed to return, it's greatly weakened compared to what it once was. It plans to change this, of course, but all things take time--and many, many sacrifices." I'm open to other things! Pre-game, AU, alternate canon paths. World building. Lore building.
Fair warning: if you can't handle in character cruelty, I'm not the one for you!
NAME: Majora
NICKNAMES: If it ever receives any nicknames I'll put 'em here
GENDER: It's been men, it's been women, it's been everything in between
SPECIES: Dragon (former), evil entity (current)
DATE OF BIRTH: Before current time
AGE: Somewhere over ten thousand years
PLACE OF BIRTH: A land before Termina
CURRENT RESIDENCE: Termina
ORIENTATION: Unknown
RELATIONSHIP STATUS: None
PAST RELATIONSHIPS: It had a friend once.
OCCUPATION: "God"
EDUCATION: Varied.
HAIR|EYE COLOR: Purple/multicolored / possession-dependent
HEIGHT|WEIGHT: Varies
ETHNICITY: Pre-Terminian
TATTOOS|PIERCINGS: Many
SMOKE|DRINK|DRUGS: no/yes/yes
DISORDERS: Unknown
LIKES: Games! Chaos! Fun!
DISLIKES: Being sealed away. Cheaters.
FEARS: None
BRIEF PERSONALITY: :)