One common theme is the exploration of the complex relationship between Jacob and Bella. It often delves into how their different natures (Jacob as a werewolf and Bella as a human/vampire) affect their mating bond. Another theme could be the conflict that arises, especially considering Bella's prior relationship with Edward. There might also be themes related to the werewolf pack's reaction to Jacob's mating with Bella.
Well, I'm not an expert in this particular fanfiction area. But you could also ask in relevant fan communities or forums dedicated to the Twilight series. People there might be able to point you to some great Jacob and Bella mating fanfictions they've read. They may have their own favorite stories based on different interpretations of the characters' relationship.
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.