The following story is fictional... I think.
Many years ago, a man died of a severe flu. He was an evil man who delighted in tormenting others, so it was no surprise that he wound up in hell.
As part of his punishment, his illness followed him beyond the void, sentencing him to an eternity of stuffy noses, upset stomachs, sore throats, and painful coughs. Satan found joy in this, smiling at every sniffle and laughing with every wheeze.
After a few years, the man's relentless sickness drove him to madness. While walking through the halls of hell, his eyes fell upon the smoldering coals lining the floor. Desperate to alleviate the pain in his throat, he snatched up one of these coals and stuffed it into his mouth in an attempt to burn a hole through his esophagus.
Surprisingly, his plan worked. And Satan took notice. He called the man into his chambers the following day to offer him a proposition.
"I know you have taken coals from the halls of my den and cured your ailment," Satan said. "I will allow you to communicate with a few of my associates in the mortal realm. They are greedy men, business associates eager to store up their wealth by any means necessary. You will inform them of your discovery, and provide them with instructions to create their own coals. In this, my most dastardly plan, I shall bring searing pain and misery upon the living through the promise of healing. And the men will become wealthy and powerful servants of mine while you become one of my trusted advisers."
The man did as Satan commanded. He appeared in a dream to one of the businessmen and instructed him how to make coals similar to those found in the halls of hell. The businessman, inspired by his vision, followed the instructions and created a new treatment for sore throats, a red coal shaped like an oblong marble, tainted with an artificial cherry flavor to distract customers from the pain, and branded with a trademark signifying their origin.
This is the origin of "Halls" cough drops.