H =

She walked in, knowing full well something was wrong. Though she inquired, he could only shake his head.
It was an equation he had perfected; a formula created for the sole purpose of knowing what, or rather who, he was dealing with. It covered it all: from the constants of gender to the complexities of the Myers-Briggs personality types arranged into a set of conditions. With this equation, he was prepared to face all sorts of people that life would send his way; excluding when zero turned up in the denominator.
He looked up for her one last time. She wasn’t there.