Perhaps there is an external threat to their mateship. A powerful villain could be trying to break them apart for some reason, like using magic or blackmail. So, they have to fight against this threat to stay together.
Another plot could be that they are on opposite sides of a conflict initially. But as they realize they are mates, they have to find a way to reconcile their differences and work together. This could involve a lot of internal struggle for both of them as they deal with loyalty to their respective sides and their new - found bond.
One possible plotline could be that they are brought together by a mysterious force. They have to figure out why they are mates and what it means for their future. Another could be that they are from different vampire clans and their relationship causes a rift between the clans. They then have to find a way to reconcile the clans while maintaining their relationship.
Another plotline could revolve around a conflict within their group, and Bella and Esme have to work together to resolve it. Their bond as mates would be tested and strengthened through this. They might have to face opposition from other characters who don't understand their relationship.
A plotline might involve Bella having to choose between different aspects of her relationships with Jasper and Emmett. For example, Jasper could offer her a more cerebral and controlled relationship, while Emmett might represent a more passionate and physical connection. Also, they could all be on a journey to discover more about the origin of their unusual mating bond.
One common plotline could be them facing challenges from other vampires who don't approve of their relationship. Since Emmett is strong and Bella has her own allure, others might see their union as a threat to the vampire hierarchy or social order.
One interesting plotline could be their adventures in the forest together. They might discover a hidden part of the forest that has some kind of magical or ancient significance. Another could be them dealing with the reactions of their respective families and friends to their relationship.
One interesting plotline could be Jasper helping Bella to control her new - found vampire abilities in a unique way. Maybe he uses his own experience with self - control to guide her.
One interesting plotline could be how they navigate their relationship in a world full of vampires and werewolves. For example, they might face challenges from the Cullen family who have different views on their relationship. Another could be their journey to understand and accept their unique bond as mates, which might involve them going on adventures together to discover more about their vampire nature.
One possible plotline could be their journey of discovery. They might start by getting to know each other's pasts, like Bella learning about Kalona's history. Another could be them facing challenges together, such as dealing with other characters who oppose their relationship. It could also involve a plot where they have to protect each other from some sort of danger in their fictional world.
One possible plotline could be their adventures together in a magical world. They might face challenges like battling dark forces and their bond as mates helps them get through. For example, they could discover an ancient prophecy related to their union that they need to fulfill.