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.
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.
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.
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.
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.
Obviously, Jacob and Emmett are the main characters. Jacob is the one who claims to be bigger than Emmett.
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.
One interesting aspect could be the exploration of character relationships within the Twilight universe. Maybe it delves into how Jacob and Emmett interact in a unique way that wasn't fully explored in the original books. It could also be interesting in terms of how the author interprets Jacob's character growth or development in relation to his 'weight' which might be a metaphor for some deeper emotional or physical change.
It could be a rather odd and perhaps unkind comparison made in the context of a Twilight fanfic. Maybe it's a statement within the story where one character is being told they weigh more than Emmett. Without more context from the specific fanfic, it's hard to say exactly.
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.
Emmett in Twilight has a unique tale. After a near-death encounter with a bear, Carlisle turned him into a vampire. He's a bold and charismatic character, adding a lively element to the Cullen dynamics and always ready to defend his loved ones.