@kranzkrone I can't talk for all fictional characters or authors, of course, but for my study here, I use exaggerated athletic dry muscle for drawing muscle groups and shapes. A bit like an écorché study.

Showing this anatomy should result in a dynamic set of lines (usually, because in my studies, I still have a lot of stiffness).

Being able to play with a mass of fat in the body, their locations, and the way they behave, is another level skill, difficult. I hope I can reach it one day.