Some people have the gift of time perception. They can remember things that would have happened, had a time traveller not gone back and altered the past. Having that gift is also a sign that you are also a time traveller.
Drake Jonston wonders why he remembers a "best friend" who never existed, The more he searches, the more he's aware of a sinister twist More
The Three Observable Facts of Time Travel
1. What really happens when you jump back to an earlier time and prevent your own birth? Do you produce a time-space paradox? Do you create another parallel universe?
No, you become a Time Orphan.
Other people may cease to exist if their birth was affected by your action, but you go on existing, because you now have a new point of origin, the earliest point of time you travelled to.
2. If, by jumping backwards in time, you change the course of your own life to the extent that you wouldn't have made the time jump when you did, you produce another instance of yourself, a Time Dopple. Dopples can coexist in the same timeline, as long as they dont come too close together. If they come within each other's event horizon, they merge back into one - one person with two sets of memories. That's because it's against the laws of physics for two instances of the same matter to exist at the same time.
3. Only certain people have the gift of time perception. Such people remember broken timelines, be it only the residue of a memory, or a deja vous. If they develop that gift, they can become time travellers themselves.
So, Isaac Asimov has his “three laws of robotics”, I have my “three facts”. All the stories in this collection are based on the above:
SAVING TIMMY BROWNING - When he was nine, Drake Johnston was sure he had a best friend named Timmy. But Timmy never existed, and everyone thought he was Drake's imaginary friend. Many years later, when Drake looks further, he finds himself on the trail of a dangerous assassin. He has help from Johann, a member of an ancient Order of Timekeepers, whose mandate is to keep history on the right track, preventing mass destruction and genocide when they can.
SAVING THE TIMELINE - In part two of that story, it's revealed that by rescuing his friend from nonexistence, he's upset a delicate balance which has triggered an international crisis that could escalate into a nuclear war. More work to do…
THE MURDER VICTIM WHO WAS STILL ALIVE - Police Inspector Dylan Murphy is working on a strange case: the body of a six-year-old boy was found buried under a pavement that hadn’t been dug up in fifty years. But the time of death was only two hours ago. What’s even more strange: the boy, Mickey Stewart, is still very much alive.
A COUPLE YEARS IN THE EARLY LIFE OF A TIME TRAVELLER - Even though the nuclear war sparked by the Cuban Missile Crisis was stopped from happening, thanks to resourceful time travellers, the memory can be quite traumatic for an 8-year-old with the gift of time perception. The Kennedy assassination a year later, also confuses his mind.
THE GREAT TIME SHIFT - The Novelette begins in the timeline in which Rome was conquered by Hannibal, and never became an empire. The Parthian Empire became the prominent world power, and Christianity spread Eastward instead of West. How one egomaniac time traveller created the great time shift that sent things moving the other way, and how the Order of Timekeepers was born.
THE LIVES OF EOIN MURRAY - In the beginning, there was only one Eoin Murray. He lived quite happily with his single mother up to the age of 4, when his future self arrived and murdered his mother. So, now there are two Eoin Murrays, the evil one, and the other who was raised in a different environment with better guidance. But once they merge back into one again, which side is dominant? How yet another Eoin was spawned, Eoin the Younger.