This article traces the evolution of Sidney Weintraub’s Post-Keynesian identity during the four decades following WW II, as seen through the eyes of his son E. Roy Weintraub. I explore Roy’s notion that Sidney’s career can be seen as the result of defense mechanisms associated with those of a borderline personality, such as splitting and projection. As Sidney transformed from an aspiring mainstream macroeconomist into a reclusive warrior for ideas, developing a polarized view of the economics profession, his work eventually became subsumed as a branch of Post-Keynesian economics. At the same time, he nudged his son into a symbiotic dependency, standing in for his career as a mathematical economist and coauthor, while also being made complicit in his adultery. Roy’s eventual distancing from this role ultimately led to a rupture prior to Sidney’s death in 1983. It was only then that Roy was able to establish a scholarly profile as a historian of economics and gain the understanding of his father that informs this text.