There could be. Fanfiction writers are known for their creativity and for pushing the boundaries of the original source material. While the idea of Bella and Emmett as siblings is not in line with the traditional Twilight narrative, in the realm of fanfiction, anything can happen. But given the rather unusual nature of this concept combined with the 'lemon' aspect, it may be a bit more niche and harder to find.
In some fanfictions, they might be reimagined as siblings. However, in the original 'Twilight' series, they are not siblings. Fanfiction often takes creative liberties to explore different relationships between characters.
Well, perhaps they discover they are siblings after some long - lost family mystery is unraveled. As they adjust to this new reality, they might face jealousy from other members of their coven. And for the 'lemon' part, it could be that there are some intense emotional moments between them that border on inappropriate feelings, which they have to overcome as they realize the importance of their family connection. Maybe they are in a situation where they are forced to rely on each other in a very close way, and those feelings start to develop, but they know it's wrong because they are siblings.
Their relationship can be shown as a very protective one. Emmett, being the stronger one, might always be ready to shield Bella from any harm. For instance, if there are other characters who pose a threat, Emmett would step in front of Bella without hesitation.
One interesting storyline could be them protecting each other from supernatural threats in their world. Since they are siblings, they would have a strong bond and would go to great lengths to keep each other safe.
One type of story could be about family secrets. Maybe there are secrets within the Cullen family that only they as siblings are privy to, and they have to work together to keep them. Another could be a story of adventure where their sibling bond helps them face challenges in the vampire world.
One characteristic is the exploration of complex relationships. For example, the love triangle between Bella, Edward, and Emmett can create a lot of emotional tension. Another is the development of unique character traits. In these fanfictions, Emmett might be shown as more sensitive or Edward as more conflicted than in the original works.
I really like 'Twilight Trio: New Beginnings'. It shows how Bella, Emmett, and Jasper interact in a unique situation, full of drama and some unexpected twists. Their personalities are well - presented in this fanfic.
In the world of fanfiction, different interpretations exist. However, in the original Twilight series, Bella and Jasper are not siblings. In a lemon fanfiction context, some might find the idea of making them siblings with adult - themed content disturbing and unacceptable as it goes against the original relationship dynamics. But in a more creative and non - traditional sense, if the fanfiction is handling it in a non - inappropriate way, perhaps just exploring a different family - like bond, it could be seen as an interesting creative take for some readers.
At first, they might be a bit distant as they get to know each other. But as time passes, they would become closer. Emmett's protective nature would come out more, and he would start looking out for Bella in every situation.