Obviously, Bella and Edward would be great main characters for a reunion fanfic. Their relationship was central to the original series, and a reunion could show how their love has evolved over time. They could be dealing with new challenges as a couple, like raising their daughter Renesmee in a world that still has some threats.
The Cullen family as a whole could also be the main characters. A reunion might involve them coming back to Forks after a long time away. Each member of the family has their own unique personality and abilities, and exploring their interactions and how they've changed since we last saw them would be really interesting. For example, Alice could be using her visions to predict something big that's about to happen in Forks again.
Jacob and his werewolf pack could be main characters in a Twilight Reunion Fanfic. They could be having their own issues in the reservation and then the reunion with the Cullens is forced upon them due to a new danger. Jacob might be struggling with his feelings for Renesmee still, and his role as a protector of the tribe. His relationship with his pack mates could also be explored more deeply during this reunion scenario.
Obviously, the original character (oc) with telepathic abilities would be one of the main characters. This oc could be a human who suddenly discovers their powers and has to navigate the dangerous world of Twilight. There could also be the main characters from the original Twilight series like Edward and Bella. The oc might interact with them in various ways. For example, the oc could use their telepathy to help Bella understand Edward's vampire nature better, or they could be in conflict with Edward because their telepathy reveals things he wants to keep hidden.
Another option is a minor character from the original series that gets a more in - depth story. For example, one of the Volturi guards who breaks away from their cold and strict regime because they meet someone special and are now willing to say 'for you' and make big changes in their life.
There could be a young unicorn named Starlight. He might be a brilliant but overconfident student who Twilight has to guide. Another character could be a pegasus named Rainbow, who is always getting into trouble and Twilight has to keep in line.
I'm not entirely sure as it's a fanfic, but it could include the main characters from the Twilight series like Bella and Edward. They might be involved in the events around the twilight lagoon, perhaps exploring it or having some kind of encounter there.
Obviously, Twilight would be one of the main characters. She could be a young and inexperienced Twilight who needs a lot of guidance from her personal assistant. And the personal assistant could be a mysterious figure with some unknown past. Maybe they have some special abilities like being able to communicate with animals which can be very useful in Twilight's world.
A vampire from the Twilight world could be a main character. Maybe he's tired of the city life and the constant power struggles among his kind. So he travels to Bear Valley Ranch, attracted by its isolation. And there, he meets a local girl who is not afraid of him and they form an unlikely friendship. There could also be an old wise man on the ranch who has known about the Twilight secrets for a long time and serves as a guide to the others.
A werewolf might be a great main character. He is cursed and during the blood moon twilight, he has to struggle to keep his humanity while also protecting his pack from hunters who are more active during this time.
Hermione Granger and Bella Swan could also be main characters. Hermione could bring her intelligence and knowledge of magic, while Bella could provide insights into the Twilight world. They might start off as rivals, with Hermione thinking Bella is too naive and Bella finding Hermione too bossy, but then they grow to respect each other and work together.
Bella and Edward are very likely to be the main characters. They are the central figures in the Twilight series, and a Christmas Eve fanfic would probably still revolve around them. Their relationship could be the focus, like how they celebrate Christmas Eve together.
The main characters are Blake and Yang. Blake is a Faunus with cat - like features. She is often quiet and reserved but has a strong sense of justice. Yang is a strong - willed and confident fighter. Their relationship is a central focus in a bumblebee reunion fanfic as they are the ones reuniting.