There's a chance that the fanfiction might introduce an original character who becomes an important part of the Glee club. This new character could interact with the existing ones and change the dynamics, which would be in line with the 'glad you came' theme as they bring something new to the group.
Perhaps it involves a love triangle within the Glee club members. One character is torn between two others, and their feelings develop in unexpected ways, which can be related to the idea of unexpected arrivals or changes as hinted by 'glad you came'.
Jacob Black could also be a main character. His relationship with Bella and the werewolf pack's connection to the Cullens might be explored in a new light in this fanfiction. Maybe his transformation or his knowledge of the supernatural world comes into play earlier than in the original story.
I think Santana and Brittany would also be important characters. They are very influential within the group. Santana's sassy attitude and strong vocals would make her a force to be reckoned with when the kids take charge. Brittany, with her unique dancing skills and her own brand of charm, could contribute in her own special way. Maybe they take charge of creating a really cool dance routine for the glee club's next big show.
The main characters would include Kurt Hummel. He would probably be in charge of the decorations, making the dinner area look fabulous. Mercedes Jones would be there, bringing her amazing voice and her big heart. Puck would also be involved, maybe causing a little bit of chaos at the dinner table but in a fun way. And Quinn Fabray, who might be reflecting on how much her life has changed since last Christmas.
In 'glee', characters like Rachel Berry would likely be a main character. She's very outspoken and talented, so she could have some great interactions with the Irwins. And from the Irwin side, Bindi or Terri Irwin could be main characters as they are well - known in the Irwin family.
I think Santana would be a key character. She has such a strong personality and her development from a bully to a more empathetic person could continue in the future story. Brittany might also be in the spotlight as she's always been a bit of an enigma and her relationship with Santana could be explored further. Additionally, Mr. Schuester could be important as he could be the guiding figure for the new generation of glee clubbers or dealing with his own post - glee club life.
Typically, the substitute teacher would be one of the main characters. They are likely to be the central figure around which the story revolves. And then, some of the students from the 'Glee' club would also be main characters. For example, characters like Rachel, Finn, or Kurt who are very prominent in the original 'Glee' series. Their interactions with the substitute would form the core of the story.
It could be some of the well - known characters from 'The Empire' who take on new roles in the context of the Glee club. Maybe Lucious Lyon could be one, bringing his strong - willed and often controlling personality into the club and causing some chaos.
There might also be characters that are minor in the original but become more prominent in the fanfiction. They could be given more complex personalities and important roles in the 'gloaming glee' story.
I think Quinn and Black Widow would be an interesting pair. Quinn is used to being in a position of power and popularity in the Glee club, and Black Widow is a strong female character in the Avengers. They could have some really cool exchanges about strength and femininity.