Bujold (World 54)
Lois McMaster Bujold (1949 – ; first SF publication, 1986) has written significant fantasy (including the Chalion and Sharing Knife series); her only science fiction (so far!) is the Vorkosigan saga. In this case, one is definitely enough. Miles Vorkosigan is one of the most interesting protagonists in print. His mother suffered a toxic gas attack while pregnant, and the antidote came close to destroying his skeletal development. The result includes frequent broken bones and a frail adult physique. However, from the earliest age, he is determined not to let his physical weakness impede his life, and as an adult, he is charming (perhaps manipulative), clever and insightful.
Most of the series depicts Miles’ adventures as a military attaché, unintentional mercenary, spy, diplomat and lord of his family’s realm. However, several books detail his mother’s exploits before marriage and one (Falling Free) takes us back a couple hundred years, to a crucial event in the development of Miles’ universe.
As part of a noble family, the Vorkosigans (in general) and Miles (in particular) don’t have much to do with commerce. However, in among the political machinations of A Civil Campaign, Miles’ clone Mark (that’s a whole other story) undertakes to breed butter bugs, which can take just about any form of biodegradable waste and regurgitate it as bug butter … which is quite tasty, as long as you don’t know the source.