The Sith Warrior's story can also be considered one of the best darkside stories in SWTOR. As a Sith Warrior, you are on a path of pure domination. You get to engage in epic battles, crush your enemies without mercy, and make choices that are deeply rooted in the darkside. For example, you can choose to sacrifice your own allies for more power, which is a very darkside - oriented action. There are also some great story arcs where you interact with other powerful Sith Lords and prove your worth through dark and often cruel means.
I'm not sure specifically as there could be many different 'darkside graphic novels'. Generally, it might be about dark themes such as mystery, horror, or the darker side of human nature. It could involve complex characters dealing with difficult situations in a dark and often gritty setting.
Nezuko is initially 12 years old in the manga. As the story unfolds, her age doesn't change significantly in a traditional sense, but her character development is quite remarkable.