Jonathan got the idea for the story from his general psychology class at Georgetown University. He pitched the idea to his brother Christopher during a cross-country road trip from Chicago to Los Angeles. His brother responded to the idea, and encouraged him to write a first draft. After Jonathan returned to Washington, D.C., to finish college, he sent his brother a draft two months later, and Christopher set to work on a screenplay, while Jonathan began finishing the short story.
-- https://en.m.wikipedia.org/wiki/Memento_Mori_(short_story)