Belle could be very diplomatic when interacting with Death. She might offer Death something in return for sparing lives or for helping her against Rumpelstiltskin. Maybe she offers to share her knowledge of the world with Death, which he might find interesting as he is usually associated with the end of life and may not know much about the living world. She could also be firm with Death, not allowing him to intimidate her into making hasty decisions.
Belle might interact with Death with fear at first. But being a strong - willed character, she would soon start to question Death's motives. For example, she could ask Death why he is involved with Rumpelstiltskin's schemes. She might also try to appeal to Death's sense of fairness, showing him how Rumpelstiltskin's actions are harming innocent people.
Belle's inquisitive mind would make her want to understand both Dead Shot and Rumpelstiltskin. She would be the one to ask questions and try to find common ground. Dead Shot, who is used to operating alone, would be a bit annoyed by Belle's attempts at first but then start to appreciate her company. Rumpelstiltskin, with his complex personality, would play mind games with both of them. He would use Belle's compassion against her and try to tempt Dead Shot with rewards. Belle would strive to bring some humanity to Dead Shot and expose Rumpelstiltskin's true motives.
One possible scenario could be that Belle, in her quest for knowledge, stumbles upon a realm where Death has a pact with Rumpelstiltskin. Maybe Belle is trying to break a curse and she has to negotiate with Death, who is using Rumpelstiltskin's magic as a tool. For example, Death could be using Rumpelstiltskin's spinning wheel to measure the fates of people. Belle then has to outwit both Death and Rumpelstiltskin to save her village from a plague that Death has brought as a result of the pact.
Another way their relationship could develop is through a series of trials. They are put in difficult situations, like having to outwit an evil witch. During these trials, they rely on each other's strengths. Rumpelstiltskin uses his cunning and magic, while Belle's daughter uses her courage and quick thinking. This mutual dependence strengthens their bond over time.
In the fanfic, Belle could sacrifice her own happiness to protect someone else from Rumpelstiltskin's deals. For instance, if her family is in danger, she might offer herself to Rumpelstiltskin without fully understanding the consequences. This act of sacrifice could then lead to a downward spiral of events that ultimately result in a tragedy. Her selfless act could be twisted by Rumpelstiltskin to his own advantage, causing her to lose more than she bargained for.
One challenge could be the acceptance of their relationship by others. Many might not understand how Belle could marry someone like Rumpelstiltskin. Another challenge could be Rumpelstiltskin's own insecurities. He might worry that he's not good enough for Belle and that his past deeds could overshadow their happiness. Also, planning a wedding in a magical world with all its unpredictable elements, like sudden spells going wrong or magical creatures causing chaos, would be difficult.
The plot could involve Belle being in a much darker situation than in the original story. Maybe she makes a deal with Rumpelstiltskin that has unforeseen tragic consequences. For example, she might try to save her village but end up sacrificing her own freedom in a more extreme way. Rumpelstiltskin, being his devious self, could twist the deal so that Belle finds herself trapped in a never - ending cycle of despair and regret.
One possible scenario could be that Rumpelstiltskin, despite his dark past, becomes extremely protective of Belle during her pregnancy. He might use his magic to ensure her comfort and safety, like creating a special charm to keep away any potential harm. He could also be seen gathering all the rare and precious items from his collection to make a perfect nursery for their unborn child.
Batman would likely be very suspicious of Light Yagami. Light sees himself as a kind of 'god' when he has the Death Note, but Batman, who is all about justice in a more traditional sense, would not tolerate Light's actions. He would probably try to stop Light from using the Death Note. As for L, they might initially be at odds as they both are brilliant detectives, but they could end up working together to stop the misuse of the Death Note.
Harry would likely be both curious and cautious when interacting with Death. He might ask Death many questions about the meaning of life and death in the wizarding world. Other characters like Hermione and Ron, if they are involved, would probably be very worried about Harry's interaction with Death and try to protect him or convince him to stay away.
Finding a specific 'Belle killed Rumpelstiltskin' fanfic can be quite a challenge. You could start by searching on major fanfic websites like Archive of Our Own (AO3) or Fanfiction.net. Use the relevant search terms in the search bars of these platforms. But keep in mind that there may not be a lot of such fics, or it may be quite difficult to sift through all the search results to find the exact one you're looking for.