I think one of the most interesting topics, to me personally, was probably my deep dive into the Illidari. They’re just such interesting trash raccoons to me. I really loved, and liked encorporating, who they were prior. I mean they had an entire life before they became what they were, and I felt that was so juicy. Not to mention the rituals, the way specific demons impacted their mental states, tendencies, and physical quirks. How they went from villains of an expansion (and their time as such) to becoming pseudo heroes who actually achieved their orders goals- and subsequently what they did in a world post-Legion. These topics and more were so fun to dive into and really helped me create my own walking Greek tragedy without it feeling forced.
Okay okay, my love for stinky demon hunters on pause- probably one of the more interesting topics I jumped into was either mechanical engineering (Kirollis) or- or- the effects that extreme gravity has on the human body. The latter was actually kinda scary to read about.