A scenario could be that Jacob has a genetic mutation in the fanfiction. This mutation makes him the largest werewolf ever. So when he is compared to Emmett, he is like a giant. He might be so big that he can carry Emmett on his back with ease. Or perhaps there is a prophecy in the fanfiction that states Jacob will be bigger and stronger than the strongest vampire, which in this case is Emmett. And as the story unfolds, this prophecy comes true, leading to Jacob being physically much larger.
Maybe in a fanfiction where the story takes a different turn in the werewolf and vampire relations. Jacob might be part of a special group of werewolves that are larger in size. And when he meets Emmett, it's clear that he is bigger. It could also be that an outside force has affected Jacob, like a magical spell or some kind of ancient power that has made him grow. In this case, he is not only bigger than Emmett but also has an air of mystery around him.
One possible scenario is during a battle or a physical competition. The author could write that Jacob has grown in size and strength due to some newfound werewolf ability or training. So when he faces Emmett, he towers over him and easily overpowers him. Another scenario could be in a situation where Jacob needs to protect Bella from Emmett. To seem more intimidating, he is described as being much bigger. For example, he stands in front of Bella, his large frame blocking Emmett's view completely.
Well, in some Twilight fanfictions, Jacob might be described as physically larger in terms of his overall build. Maybe he has broader shoulders, more muscular mass that makes him seem even bigger than Emmett. It could be emphasized through descriptions of their encounters or when they are standing side by side. For example, the author might write about how Jacob's presence seems to overshadow Emmett's, not just in height but also in the width and power that his body exudes.
On the other hand, it could also lead to a change in the power dynamic. If others in the 'Twilight' world take Jacob's statement seriously, it could mean that Jacob is seen as a more dominant figure compared to Emmett. This might affect how other characters interact with them. For example, if there are battles or group decisions, Jacob might be given more authority based on this claim.
Well, it could be about a physical competition between Jacob and Emmett. Maybe they are competing in something like strength tests in a fictional world where their sizes play a role in the outcome.
In some Twilight fanfictions, Jacob's werewolf form might be described as larger in terms of physical stature compared to Emmett's vampire form. Maybe it's about his height, or his overall build when transformed. For example, his werewolf shape could be more bulky and take up more space, while Emmett, though strong as a vampire, might be more streamlined in comparison.
Another possibility is that it's a statement of self - confidence. Jacob could be trying to assert himself over Emmett. He might be in a situation where he wants to show that he is not intimidated by Emmett. Maybe he is competing for something, like Bella's attention, and by saying he's bigger, he's trying to prove his worth and superiority in that regard.
Obviously, Jacob and Emmett are the main characters. Jacob is the one who claims to be bigger than Emmett.
One example could be in battle scenes. Jacob in his werewolf form might be described as towering over Emmett, his large paws and muscular build making him seem much larger. Another instance could be in descriptions of their auras. Jacob's werewolf aura might be depicted as more expansive, symbolizing his 'larger' presence compared to Emmett.
One possible scenario is that Jacob reveals a secret that Bella doesn't like. This could make her feel betrayed and start to hate him.
You could try searching on popular fanfic websites such as Archive of Our Own (AO3). They have a large collection of Twilight - related fanfics, and there's a good chance you'll find it there.
One possible scenario is when the imprint causes Jacob to be very protective of the person he imprints on. Bella might see this as Jacob neglecting their previous friendship or bond. Another scenario could be that the person Jacob imprints on has a negative attitude towards Bella, and Jacob seems to side with the imprinted one, making Bella hate the whole situation.