Hi! First, let me tell you, I am not really interested in making my own rpg engine (at least not in the near future, hehe), but I do feel like I want to understand the internals of how a rpg engine works.
Why? Well, because I like to read about programming and design, It keeps me motivated and excited, and because I know I will learn a lot, for, even when I have been programming for some years now, I never stop considering myself an ignorant... there are simply SO many things involving a game engine (specially rpg ones, like branching storylines, and items and economics!) I'm eager to know.
I've been searching (and thus, finding) lots of info online, but it is never focused in what I'm interested (most of it talks about the mathematics and AI algorithms implementation, which I know quite well), which is the design of overall structure, patterns, scripting engine, decision engine... damn, so many things I can't even imagine, since I've never done any game programming.
I hope you know have an idea of how I feel, and how I want to learn for the sake of learning, and why would I want you to tell me if you know if there exist books touching the topics that interest me the most.