Mer often wondered how different life would be—how different he would be—if his father had not died when he was four.
As best as could be reconstructed, Mer figured that his father died right about the time the mailman delivered to their house. Given his father's very obvious collapse in the middle of the living room floor, it would only have taken a glance, nothing more than a swivel of the neck, for the mailman to see the body through the open front windows. Maybe he would have gone inside the house to check on Mer's father, or maybe he would have radioed in (or whatever mailmen did before cell phones) for an emergency response. It could have happened, so very easily, that Mer was sure it had. He was certain that out there in the multiverse was a version of him who grew up suffering under the bastard's untender, unloving care, and he often took time to feel sorry for the schmuck he might have been.
On that glorious day, Mer was at the special school which his father hated so much, the one where Mer first learned how to divide really big numbers and discovered the mysteries of the isosceles triangle. Mer imagined that if his father lived, he would have eventually forced Mer into the public school system with "the normal kids" simply because the special school was so expensive. It was why Mer's mother worked two jobs, in order to pay for that school, and as amazing as his mother was, he knew she could not have kept that up for too long. Certainly not as she got further along with Jeannie, who was still an embryo when their father kicked off his mortal coil.
If their father did one thing right, it was to take out a really large life insurance policy when he was a young man, many years before his heart gave up on him. The half-million dollar policy was unheard of, and Mer suspected his father did it so he could simply cash it in later. Fortunately, it was their mother who cashed it in, and in the terms of 1973 currency, a half a million dollars was the McKay ticket to a better life.
There was never any doubt where Mer and Jeannie got their brains: it was their mother who invested the money, paid off the house, set aside funds for their college careers, and proceeded to shepherd her progeny to greatness. Jeannie won a Nobel for Chemistry in 2004, and while that sometimes had Mer spitting nails it was simple sibling rivalry, not true professional envy. He was proud of her. Anyway, he got Atlantis, and he figured in the great scheme of things it was a fair trade.
But that was all because one unknown, unremembered mailman did not bother to turn his head one late afternoon in 1973. Life could have been so different, so much worse, that Mer really did not like to think about it.
He always introduced himself as Dr. Rodney McKay; he was careful to keep up appearances. To family and friends he was “Mer” but to the world outside, where everyone was a competitor and no one could be trusted, he was Rodney McKay. It kept relationships in boxes, right where he liked them.
But when he finally met another Dr. Rodney McKay—the person no one called "Mer" and who lived as a stuttering, blustery shadow of a truly great man named Lt. Col. John Sheppard—that was when Mer saw how bad it could have been.
After meeting his universe's version of John Sheppard, he realized that for every win in life, there was a loss. He wondered what singular point along the timeline sent Detective John Sheppard down the path to oblivion. Was it nothing more than the twist of a head? Or was the great Colonel Sheppard a product of an entirely different set of circumstances? Mer would never know.
In the days after The Event, when Sheppard died twice on the operating table and Radek was demoted and Mer had entirely too much time on his hands to ponder “what ifs”, he sometimes visited Sheppard’s hospital room. The detective was in a medically induced coma and would be for a while, so Mer got all the time he wanted to study his profile and reread his file.
Mer felt like this was his one great chance to change history, even if it wasn’t his own.