Doc Sudo Ersatz is a skilled maker of potions using the oil from serpents that come from Mars' artisanal wells. Ersatz created potions which made Croach the Tracker feel happiness, Felton to experience bravery and Pemily Stallwark to experience peace.
He is also an assassin, just as his parents before him were, and wished for him to be as well. He's a people pleaser.
Ersatz came to Mars with a plan to assassinate Sparks Nevada for unknown reasons. He concocted a complicated plan hinged on getting several of Sparks' friends to visit Ersatz and recommend his services. Then, while Sparks was walking back to The Marshal Station with a bowl of chili, Ersatz teleported a bug into Sparks' eye, causing him to jab a chili-covered finger into his eye, then fling away his bowl of chili which was also holding his marshal badge into a group of nearby cactoids. When Sparks went back the next day and couldn't find his badge, and received a bump, rash and limp for his troubles, this caused a newly-blissful Croach, brave Felton and peaceful Pemily to insist Sparks visit Ersatz. After Ersatz teleported Sparks' badge back into his hand, confusing Sparks as to how it'd gotten there, Sparks agreed.
While visiting Ersatz, Sparks revealed that he'd been having a recurring dream of a cat in a patch of sunlight bathing himself "like a frenchman". Ersatz, meanwhile, concocted a potion that was actually a poison to kill Sparks. Eventually, Sparks noticed the teleporter with a scope on it in Ersatz's office, and also that Ersatz was making his potion entirely from a vial with a skull and crossbones on it.
After figuring out Ersatz was the assassin, Sparks arrested Ersatz. However, before being taken to jail, Ersatz revealed that Croach had been having the same recurring dream as Sparks, possibly to mess with Sparks' head, but possibly not.
- Space Oil (TAH #175)