They say that a Hero's work is never done.
That if they ever stop working for even a moment, be it for family, their health, or for another, all that they love will be torn away from them.
There exists a timeline where three heroines unintentionally discovered this curse, finding themselves in a future 50 years without them ruled and terrorized by their most fearsome foe, and all the blame on their error of judgement.
In another timeline, a young boy was told of his great power. As his life was turned upside down in all ways, he fled from his home with only his trusted steed. He promptly got frozen in an iceberg for 100 years, waking up to a world where his absence led to a horrible war.
But this is not about them. Their history with the Bureau is another story in of itself.
No, another hero, from a world not far from them in the grand scheme of things, had learned this lesson. On the call of heroism and of those who needed help, he had left his home planet of Earth to save another, and had been gone for a year.
And when he returned......
"A human?" the disturbingly smiling red horse that looked scarily like his grandfather, and sounded like him, told him a tone that was normally reserved for something repulsive "How is it you are still alive even in the barrier?"
"Mana field in effect: recently installed protection protocols engaged" the watch on his wrist beeped, answering the question for him.
"Don't worry, we'll soon have that fixed" the creepy Grandpa pony smiled at him, a smile so demented that even his local vampire zombie clown (and yes he did have one of those) would find creepy, as the mockery began to approach him.
His face never changing.
Not a single bit.
....
His name was Ben Tennyson.
He was a Hero of Heroes. He saved the galaxy several times, with the lowest count currently on record being about 3 times.
He bore a device known as the Omnitrix, a powerful alien device that allowed him to take any shape he so desired.
Yet with all of this power, he had never once felt so alone.
But that is what a planet of mad horses would do to the world's last human.
It made you feel so alone.
So very alone.
....
As a young man, he had been many things.
As the fiends attacked, a being covered in flames and magma blew them away.
Cocky.
A blue blur impacted into them rapidly, again and again striking them down.
Showboaty.
A large yellow ball impacted against dozens of them, striking them harsher than any special effects in a temple production.
Lazy.
As a blur rose out of the ground, a blue freezing smoke rose up. The horned foes he faced found themselves trapped in a frozen prison.
This was not the time for that.
A large being made of stone held his arm out against a winged attack formation. All who approached him hit the ground with a thump, gravity turned against them.
He had to be different now. This was not an age for someone to have fun.
Green crystal impaled all who drew near.
This was not an age of heroes anymore.
A turtle, spinning like a fan, formed a mighty wind attack to strike at hundreds of the transformered
It was the age of avenging.
A growling orange Tiger roared over a pile of those he had torn apart.
it was no longer the time to be a human
A four armed alien held unicorns with severed horns in each hand, squeezing.
Over time, Ben 10 ceased to be.
An army of small, white aliens unleashed a might sound attack in all directions of a leading Pony.
The hero was dead.
As a dozen of the transformed slaved away at making more vile fluid, a green ooze seeped into the room, taking shape behind them. Then the shape flashed green, revealing a snarling orange beast.
A protector would rise in his place.
As a red manta like alien fly through the skies, several dozen Pegasi flew in pursuit. A dogfight with lasers and storms ensued.
He would go by a new name, a single name all his forms would be known as.
A metallic alien vanished, going back in time to before everything broke.
Ben 10,000.
As a barrier approached the coast of America, a giant being rose up from the waters in front of it ready to destroy everything about it, without mercy.
....
As the battle raged, one champion against an army the world saw the start of a new future.
A new Ben.
Many would cheer his praises.
His loved ones....would wonder what happened to the boy they loved.
....
The 10th world was saved, even as 42 more lay in danger (though given time travel one could argue the 10th world was actually the 52nd, but for simplicity sakes one will ignore the horrible future)
But who would save the savior? The one broken by the dark and horrible future.
A time loop would soon develop, temporally speaking at least: for one of the loved ones of the savior would snap him out of his dark and broody days with his younger self, who himself would grow to be broken by the Equestrians and need to be restored by his younger self.
It was a headache for the local time traveling professor to deal with.
"Magical Genocidal Pastel Horses From Another Universe Stream......even by my standards that is odd...." the white labcoated professor mused from the moon, even as he watched the pink light on earth shatter "What's next?"
"That is a good question."
Turning, the professor found himself staring at one of those very horses, but brown and seemingly not mad.
They looked at one another awkwardly for a moment, before the professor held out a pair of round balls.
"Gumball?"