Dr Ereboam was a Tleilaxu Master Researcher in charge of their Kwisatz Haderach project during the time of the Ascension of House Atreides. Dr Ereboam invested heavily in his created clone Thallo, whom he believed to be the super-being.
As Thallo was decanted on Tleilax in Thalidei, Ereboam kept the young man's faults and personality quirks hidden from his fellow Masters. Thallo developed a desire to "cut" his skin to produce blood, with other strong feelings; Ereboam kept this secret underground for years. As Thallo reached the age of adulthood, Ereboam invited Count Hasimir Fenring, Lady Margot Fenring, and their daughter, Marie Fenring, to the Thalim system; to observe the Tleilaxu's method of twisting personalities.
Later, when Thallo's personality completely failed, Thallo decided to "make a statement" to his creators about their failed Kwisatz project. This involved killing himself, Marie, and all the inhabitants of Thalidei. Marie, having been trained as a Master Assassin; killed Thallo first. Even as these events occurred, Ereboam wished that perhaps Marie was to blame; but after reviewing the evidence, realized that Thallo was indeed deeply flawed.