Charles II, Duke of Burgundy, Archduke of Austria inherited the crowns of Spain through an untimely series of deaths of the Trastamara or half-Trastamara heirs. His uncle, Juan of Aragon, Prince of Castile (both through blood and by marriage) died in 1497 of tuberculosis, leaving a pregnant widow, Margarethe of Austria-Burgundy. Sadly, Margarethe was delivered of a stillborn daughter.
Now for the POD – requiring of a double butterfly: Juan and Margarethe have a son, born alive, and eventually succeeds to the Crown of Castile in 1504, and, providing his grandfather doesn’t pull his OTL stunt and try for another male heir, to the Crown of Aragon in 1516.
What do you guys think?