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 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.
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.
He might become withdrawn at first.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.
In such a fanfiction, it could be a really dark and complex story. Maybe Dagur uses threats or some form of blackmail to force Hiccup into this situation. Hiccup, being the strong - willed character he is, might initially resist and try to find a way out. However, if he has no other choice, he could be forced into a marriage that goes against his true feelings. This could lead to a lot of internal conflict for Hiccup, and also a strange and tense relationship between him and Dagur.
One possible plot twist could be that Bella discovers Edward has a secret identity that is not what it seems, like he's part of a supernatural group she didn't know about. This could change her perception of the forced marriage and add a whole new layer of drama.
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.
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.
I'm not sure of an exact one off the top of my head. But if you browse through the Twilight section on fanfiction sites and filter by your criteria, you should be able to discover one that suits your interest. Different fanfics might offer different takes on this alternate storyline.
Well, in some fanfictions, Bella might be scared of Edward because of his vampiric nature. His superhuman strength and speed could be intimidating. Also, the unpredictability of his actions as a vampire who is constantly fighting his bloodlust could make Bella feel scared.