Louis Lupin is discussed by Philip José Farmer in his books Tarzan Alive. He is described as having been coachman to Honoré Delagardie, rescued alongside his master from the dangers of the French Revolution by Sir Percy Blakeney. All three men were present at the Wold Newton Meteorite strike. It is at least implied that Louis was the ancestor of master-thief Arsène Lupin, but in Doc Savage: His Apocalyptic Life Farmer announced his intention to focus on the master-thief's ancestry in a further journey into biography that unfortunately never took place.
Copious later research has been undertaken into the life of Louis Lupin by the authors of the French Wold Newton Universe website, which confirms Louis as the ancestor of Arsène. Here, it is revealed that Louis was an illegitimate son of Carlo Buonaparte, making him the half-brother of Napoleon. Louis was not really a servant, but a member of the Conspiracy that would direct the future history of France. He was also said to have fathered Charles Dupin upon Honoré's wife, and that his "Dupin" descendents were actually all named "Lupin".
A rival theory, hosted at the same website and discussed by researcher Vincent Mollet, recommends the theory that Louis Lupin was actually (the much-younger) Dauphin, the rightful King Louis XVII. Jean-Marc Lofficier has wittily tied the two Francophile theories together, suggesting (not with any great seriousness) that this would make" Napoleon the bastard heir of the Bourbon dynasty"