The character of Mercer was concocted by an unidentified party who created a series of fifteen-minute films featuring Jarry as the character. Jarry never met his employer.
According to the story of Mercer, as recalled by John Isidore, Mercer was found as a baby by Frank and Cora Mercer, floating upon a rubber rescue raft in either New England, Mexico, or Tampico. During his childhood either on Earth or a colony world, Mercer had a particular fondness for animals and discovered he had the ability to bring dead ones back to life.
When Mercer was sixteen, the local law ordered him to cease practicing his ability, which he continued to do in private in the woods until he was arrested after being reported by an elderly woman. The authorities subjected his brain to radioactive cobalt and he found himself in another world that he could not escape until repairing the animals whose body parts were strewn about. Eventually, the animals were repaired, either by Mercer's brain healing or a natural process, allowing him to ascend up a hill, pelted by rocks.
Behind the scenes
He later appeared in Do Androids Dream of Electric Sheep?, its comic book version, and the prequel, Dust to Dust. Since Mercerism was left out of the film adaptation, Blade Runner, it has no character based upon Mercer.