Time
Boundless. Unstoppable. Eternal.
These are but a few of the aspects which color the human perception of time. But long ago, before time as we know it, when the universe was nothing but a yawning void of Chaos, something stirred in the darkness. All of existence was born in a single, miraculous moment of blinding light, and in this time before time, entities wholly unlike any living thing that would succeed them came into being.
They have been known by many names throughout the eons. Some see them as gods, while others consider them personifications of time itself. The Watchers, as they would later be called, have always remained a tantalizing mystery to the civilizations of lesser beings that marveled at their greatness. All that is truly known about them is that they were witnesses to all of time from the very beginning. Every hour, every minute, every second. Each moment in time from the dawn of creation to the cold, silent death of the very last star. They saw the entirety of time from beginning to end, and as they began to understand that the end of existence would mean the end of themselves as well, they decided to take action to preserve it.
Not all of them agreed on how this should be done, however, and their disagreements eventually evolved into conflict. The first denizens of the primeval universe went to war amongst themselves, and the cosmic forces they wielded against each other in their battles gave shape to the galaxies and solar systems which would fill the chasm of endless space. In the end, one Watcher emerged victorious: Chronos, who thereafter would be known as Father Time.
Still, all was not well in the universe. The titanic clash between the Watchers, although finally resolved after countless millennia, had damaged the fabric of time in terrible, unforeseen ways. This fractured reality could not exist in such a state for long, and so something had to be done to ensure all of time did not collapse in on itself. Father Chronos, in his infinite wisdom and boundless might, drew the cracks running through time into himself at a point in space where they all converged and sealed the damaged portions of reality away in a dimension outside of time. This feat greatly weakened him, however, and so he was forced to remove himself from the time stream as well in order to rest and recover his powers.
This process would require innumerable years to complete itself, and so Chronos left behind a group of servants to watch over the universe for which he had sacrificed himself. These servants would eventually rally around the place where Chronos sealed himself away, using it as a nexus to travel throughout the past, present, and future. They were dedicated to maintaining the time stream in accordance with their master's wishes, and so the Servants watched over the nexus and the planet that (perhaps not) coincidentally formed around it.
This planet would eventually become known as Earth, although relatively few of the people who have called it home throughout its history are aware of the Servants of Time and the work they do. But on rare occasions humans by accident do discover the secret places around the planet where remnants of the rifts in time Chronos sealed away can be found. For those unfortunate enough to stumble into these so-called "rabbit holes", it can mean finding themselves emerging in places and eras completely unfamiliar to them. Luckily for them, it is the job of the immortal Servants of Time, who are also known as Timekeepers or White Rabbits, to pluck these time-tossed souls out of danger and return them to the time from whence they came.
The Timekeepers are an enigmatic lot, but their calling card throughout history has always been the same. Each Servant of Time whose duty it is to retrieve those who are lost and temporally displaced carries with them a talisman in the form of a pocket watch, the face of which is engraved with the image of a white rabbit. This magical watch allows them to travel through time at will, but if they are ever separated from their watch a Timekeeper will begin to rapidly age until they disintegrate to dust.
It's a dangerous and thankless job, but as with most jobs, dangerous and thankless or otherwise, somebody has to do it.
