They could be very protective. After all, Edward is their son. So they might be a bit cold to Bella at first, sizing her up.
One possible reaction is that they are overly friendly right away. They might be so glad that Edward has found someone he loves that they welcome Bella with open arms. However, they could also be reserved and polite but keep their true feelings hidden until they know Bella better. For instance, they may ask her a lot of questions about her family and her life to understand her better.
They could be skeptical. They might wonder if Jaden has good intentions towards Alexis. So they could be a bit cold at first, observing Jaden closely and waiting to see how he behaves. This would put Jaden in a tough spot, having to work hard to win them over.
Draco's father, Lucius, might be very disdainful at first. He has a strong sense of pure - blood superiority and Hermione is a Muggle - born. His mother, Narcissa, might be more reserved in her dislike. She could be more focused on how Hermione's presence affects Draco.
Bella would likely be very frightened during the car incident. Once Edward saves her, she'd be extremely relieved and probably feel even more attached to him. Edward, on the other hand, would be initially worried and focused on getting Bella to safety. After saving her, he might feel a sense of relief as well, but also a bit of that over - protective feeling that he often has for Bella.
In this kind of fanfiction, there could be a lot of tension. Maybe Bella is really nervous to meet them as she loves Edward. His parents might be initially skeptical of her, but as they get to know her, they start to see why Edward is attracted to her.
Edward might seek revenge if he believes Bella's death was caused by someone. He would use his vampire abilities to track down the supposed culprit. For example, if he thought a rival vampire or a group of humans were involved, he'd be relentless in his pursuit. His sense of loss would fuel his anger and drive for vengeance.
Jacob might feel extremely angry. In the Twilight series, Jacob has strong feelings for Bella. Seeing her kiss Edward would be like a slap in the face. He could feel betrayed and might even lash out at them.
In fanfiction, Edward's reaction could vary greatly. Some stories might depict him as being overjoyed and excited, ready to embrace fatherhood. However, considering the unique situation of a vampire and a human having a baby, he could also be very apprehensive. He may think about how the baby will grow up, whether it will be accepted in their world. He might also be concerned about Bella's transformation, if that becomes necessary for her survival during or after the pregnancy.
Her parents could be shocked at first. They might be disappointed if they had high hopes for Bella's academic future. But some parents could quickly shift to being supportive. They would start thinking about how to take care of Bella and the baby, like arranging for proper medical care and ensuring Bella has a healthy diet during pregnancy.
For Edward, there's likely a mix of relief and fear. Relief because he's finally expressing his deep love for Bella, but fear because he's exposing his true feelings and also worried about how this will change things. For Bella, she's probably mostly filled with excitement and a bit of shock. The excitement of this new level of intimacy with Edward, and the shock that this moment she might have dreamed of is actually happening.
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.