Sure. There might be some new characters created specifically for this fanfiction. Maybe a wise elder in the werewolf community who gives advice to Jacob about how to handle the situation with Bella and the pregnancy. Or perhaps a human friend of Bella's who discovers the truth and has to deal with the shock of the supernatural world.
Bella herself might struggle with her identity. She has been so caught up in the vampire world before, and now being with Jacob, a werewolf, she has to redefine who she is and where she belongs. She may also worry about how her human family and friends will react to her being with a werewolf.
A dominant Jacob is usually in touch with his alpha side. This means he has a natural leadership quality. He can command respect from others in the fanfiction world. And when it comes to Bella, this leadership translates into him guiding their relationship in a way that he believes is best for both of them. He may be more confident and self - assured, which can be both appealing and a source of conflict in the relationship with Bella.
One character could be Seth Clearwater. As a member of Jacob's pack, he could play an important role in their married life. Maybe he helps them out in times of trouble or is like a younger brother figure to their family.
It would become more intense and complex. Jacob would be very protective, his werewolf instincts kicking in fully. He'd be constantly worried about Bella and the baby's safety.
Often, it portrays Jacob as being extremely protective of Bella due to the imprint. He is shown to put her needs above his own and be willing to sacrifice a great deal for her. For example, in many stories, he will fight against other threats, be it vampires or other werewolves, to keep Bella safe.
An unexpected guest could be a human who has some sort of special ability to see the supernatural world but has been hiding it. This person could come forward at the wedding and reveal that they know all about the vampires and werewolves and that they have a message from a higher power about Jacob and Bella's relationship. It would be very unexpected as no one expected a normal human to be involved in such a way.
In some fanfictions, Jacob and Bella's pregnancy can take on various plotlines. One possibility is that it creates a huge rift between the werewolf pack and the Cullens. Jacob's loyalty to Bella is tested as he tries to protect her and their unborn child from the potential threats in the Twilight world, like the Volturi. This situation often leads to a lot of drama and tension in the fan - created stories.
One common theme is the love triangle between Jacob, Bella, and Edward. Many fanfictions explore how Jacob's feelings for Bella develop and how she navigates her relationships with both of them.