Well, it could be many things. Maybe Hermione was shocked at first. Then, Narcissa might start to explain her actions, perhaps she was trying to protect Hermione from something or someone that was about to enter the room.
One reason could be that Narcissa misinterpreted Hermione as a threat to her family or something she holds dear. So she pushed her on the bed as a quick way to immobilize her.
One possible motive could be that Narcissa has some sort of misunderstanding. Maybe she thinks Hermione is a threat to her family or has some crucial information related to the wizarding world that she wants to extract. Another reason might be related to the power struggle within the wizarding community. She might be using Hermione as a pawn in a larger game that involves different factions.
She might have been shocked. Hermione is usually a composed character, but such an unexpected physical action from Fleur could have caught her off - guard, leaving her momentarily stunned.
Maybe there's a magical artifact that both Hermione and Narcissa are after. Hermione gets to it first, and Narcissa, in her attempt to retrieve it, restrains Hermione to the bed. She could be planning to force Hermione to give up the artifact or tell her its secrets.
Maybe Fleur was just being playful. In some fanfictions, characters might have these sorts of physical interactions as a form of friendly teasing or a quick, impulsive action without any real harm intended.
Hermione would likely be defiant at first. She is a brave and strong - willed character. So, she would probably try to resist Narcissa's attempts to intimidate her and would look for ways to escape immediately.
There could potentially be a fanfiction with that description. However, it's not a very common or mainstream concept. Fanfiction often explores unique and sometimes controversial relationships and situations. But this might be considered a bit out there, and it may be difficult to find unless you search through some less - regulated or more extreme fanfiction communities, which I don't really recommend as they may contain inappropriate content.
The husband might have been seriously injured or unfortunately died. If he survived, there would be a police investigation to find out the reason behind the wife's action, whether it was due to some long - standing domestic issues, mental health problems of the wife, or some other immediate conflict.
Common themes in 'narcissa and hermione fanfiction' include forgiveness. Given their different backgrounds and actions in the main story, forgiveness becomes a crucial part of their relationship development. There's also the theme of discovery. They discover new things about each other, like Hermione might discover Narcissa's hidden kindness and Narcissa might find Hermione's unique wisdom. Mystery can also be a theme, like when they work together to solve a mystery that involves their families or the wizarding world at large.
You can start by looking on fanfiction platforms like Archive of Our Own (AO3). Just search for 'Hermione x Narcissa secret relationship' in the search bar, and it should bring up relevant stories. AO3 has a large collection of fanfics in various genres and themes.