The first reports of Merritt come from when he enrolled at Oxford in 1877. A contemporary of Oscar Wilde, he was described by the writer as humorless and "like the winter in a seaside town,". Merritt was a dedicated scholar who threw himself into his studies and ignored extra-curricular activies like plays and sports. Shade commented in his journal that he seemed destined to become a gray scholar (one whose knowledge comes from study and not experience) were it not for his developing an interest in the occult.
In 1879, Merrit was successful in summoning an demon. The two made a typical Faustian bargain; in exchange for immortality, Merrit would become the guardian of a poster that was a portable gateway through which the demon could snatch the souls of others. Merrit left Oxford a month later to begin traveling the world.
He traveled the world during this time, taking up numerous jobs in numerous places. He was a sailor, political advisor, spy (for the Dutch and the Turks in separate wars), politician (a street in an Australian suburb still holds his name, we are told), actor, arms dealer, riverboat gambler, brewer (during the American Prohibition of alcohol), mail-plane pilot and solider. He also acted as an assassin, taking fees to place his poster in a particular spot to make sure that a certain person would be snatched by the demon.
In the 1920's, Merritt and his poster became the obsession of a British detective named Hamilton Drew, who persued the two until he was ultimately consumed by the demon himself. There were only two rumors of Merritt and his demon after that. One came in the 1940's when the demon was fought by an American detective named Jonny Peril. The other came from Gotham City, where the demon in the poster fought The Demon Etrigan.
Merrit came to Opal City in the 1990's, where his presence was discovered by The Shade, who had long been trying to find the other immortal. His soul was taken by the Poster Demon after Jack Knight, Matt O'Dare and The Shade each agreed to give up their souls to release all those who Merritt had helped capture. One of the various rules regarding demons making pacts forbids demons from making any bargain that is not mad for a selfish gain. Since the three hero's bargains were selfless acts of sacrifice, the demon couldn't take their souls but he had to keep his part of the bargain. This resulted in the all of the soul's captured by Merritt being released into modern-day Opal City and in Merritt being taken into Hell by the demon.
The Poster Demon allowed Jack, Shade and Matt to leave his realm but warned them that he would return one day, emerging through the sketches of a sidewalk chalk artist.