She could seek help from her friends, like Jacob. Jacob has always been protective of Bella. He could interfere and try to convince Edward that forcing Bella into marriage is not the right way. Also, Bella could use the support of her father. Her father might be able to have a man - to - man talk with Edward and make him see reason.
She could try to reason with her parents. She could tell them that she doesn't love Edward and that forcing her into this marriage will only make everyone unhappy. She could also point out the modern values of freedom in choosing a life partner.
The relationship develops in a rather complex way. Since Edward pays Bella to marry him, there's an initial power imbalance. However, as they live together, they start to understand each other better. For example, Edward might learn about Bella's dreams and fears, and Bella might come to understand Edward's reasons for his actions in the vampire world. This leads to a deeper emotional bond that goes beyond the initial transaction.
One possible reason could be his over - protectiveness. Edward might think that marriage would legally bind Bella to him and he could better protect her from the various dangers in their world, such as other vampires. He may believe that as his wife, he could keep a closer eye on her.
One possible plot could be that Bella initially refuses because she feels insulted by the idea of being paid. But then she realizes Edward has some deeper, unspoken reasons for his offer, like protecting her from some danger in the vampire world. So she agrees and they start a journey full of secrets and unexpected twists.
Hiccup could try to resist by using his intelligence. He might find loopholes in Dagur's plans or demands. For example, if there are certain cultural or traditional rules that Dagur is using to force the marriage, Hiccup could find ways to show that those rules are being misinterpreted or misapplied.
He might become withdrawn at first. Since he's used to being in control and having a certain dynamic in their relationship, Bella's anger could shock him into pulling back. He could go off on his own for a while to think about what he did wrong.
Together, they would likely try to make Renesmee understand that their relationship is special and that her presence is also special. They might give her a hug or some form of affectionate gesture to show that they are a family unit and that her walking in is just a normal part of family life, even if it was an intrusion on their private time.
It often starts with attraction. Edward is drawn to Bella's unique scent and her differentness. Bella, on the other hand, is intrigued by Edward's mysterious nature.
Bella might become more rebellious at first. The idea of being forced into a marriage goes against her independent spirit. So she could start to act out, be more outspoken, and challenge the authority that is forcing her into this situation.
It redefines it by making it unequal. Bella is in a position of being 'owned' in a sense, which is a huge change from their normal relationship where they are more like equals in love.