I'm not entirely sure as there could be many different 'lycoris light novels'. Generally, it might be about some fictional stories perhaps involving characters, a unique plotline, and a particular setting. It could be about adventure, mystery, or relationships within the world created in the novel.
The story of Sword Art Online Lycoris is set in the virtual world of Sword Art Online. It likely involves the typical elements of the SAO franchise such as characters battling in a virtual realm, facing various challenges, and forming relationships. It may also have new storylines, characters, and twists specific to the Lycoris part of the story.
One common theme is friendship. Just like in the original series, fanfictions often explore the deep bonds between the Lycoris girls. For example, how they support each other during tough times.
Without knowing the exact 'lycoris light novel', it's difficult to determine the main characters. But typically, light novels feature characters that readers can relate to in some way. There might be a main character who is a dreamer, always longing for something more in their life. There could also be a mentor - like figure who guides the protagonist. And perhaps there are some antagonists who oppose the main character's goals, creating conflict and driving the story's development.