I think 'The First Heretic' is very popular. It has a complex plot that involves the fall of the Night Lords legion from their original state. It also has great character development for the main characters within the Night Lords.
One of the notable Night Lords in novels is Talos. He is often a central figure, showing the complex nature of the Night Lords. He has his own moral code, albeit a very twisted one compared to most protagonists.
The Night Lords in novels are often characterized by their nihilistic and sadistic tendencies. They don't just fight for victory; they seem to take pleasure in the suffering of their foes. Their origin stories usually involve some form of dark pact or a fall from grace. Their appearance might include elements like spiked armor and dark symbols. They are also likely to be masters of infiltration, able to slip into enemy lines unnoticed and wreak havoc from within. Their culture within the novels often revolves around a cult - like worship of their own power and the ability to instill fear in others.
I'm not sure specifically as there could be various themes. Maybe they focus on the dark and brutal deeds of the Night Lords legion, their campaigns, or the inner workings of their traitorous society.
One of the main characters is Sevatar. He's a complex and somewhat enigmatic figure within the Night Lords legion. His actions and decisions often drive the plot forward.
It could be significant in that it shows Bricky's interest in the Guardsman universe through fanfiction. Maybe Bricky is exploring different aspects of the Guardsman story that the official canon doesn't fully cover.
Well, without having read 'the lords of night a shadow bruja novel', it's hard to say exactly. However, given the title, it may center around a group of powerful beings, the lords of the night. The 'shadow bruja' part makes me think there could be a witch - like figure associated with shadows. Maybe they are in a world full of magic and danger, and the story follows their adventures or their fight against some dark forces.