There might also be new characters created specifically for this fanfiction. Maybe a young, talented witch or wizard who Harry discovers and brings into the Order. This new character could bring fresh ideas and a different perspective to the group, while also having their own story arc within the fanfiction.
Obviously, Harry would be one of the main characters as he is the one doing the cooking. Members of the Order like Sirius Black could be main characters too. He might be the one who encourages Harry to cook for the group or gives him some special cooking utensils or ingredients from his family's collection.
It's hard to say for sure without reading it, but it could be Harry Potter himself. He often finds himself in the middle of things and might be involved in establishing or dealing with the power of order. Hermione could also be a main character as she is intelligent and would likely play a role in any new system of order. Ron might be there too, providing his loyalty and courage.
It's likely that Harry Potter himself would still be one of the main characters. Hermione and Ron would probably also play important roles. However, there could be new characters introduced as well that are central to the new order concept.
Obviously, Harry Potter himself is a main character. He is likely at the center of the story as he usually is in any Harry Potter - related plot. He'll be the one facing the challenges and growing as a wizard.
Remus Lupin would likely be a main character. Since he is a werewolf himself and has a connection to Harry, he could play an important role in the story. He might be Harry's advisor on werewolf matters, or even help him in leading the pack.
Obviously, Harry himself is very important. Then there's Sirius Black, who could play a big role in guiding Harry within the Order. Dumbledore would also be crucial as the leader of the Order.
It could be a rogue member of the Order. Maybe someone who has their own agenda and decides that Harry is a threat to their plans. So they manipulate the Order into kidnapping Harry, but then they have their own evil intentions for him.
Obviously Hermione is one of the main characters. As for the others, it could include members of The Order such as Dumbledore, Sirius Black if he was still alive in the context of the story, and other Order members who are involved in the act of betrayal.
Another possible main character could be a historian or a scholar within the order. Their knowledge of the past could be crucial in helping the order navigate the historical period they travel to, and they might also be on a personal quest to discover something that has been lost in time.
Among the popular characters in 'Harry Potter Order of the Phoenix' fanfiction are the Weasley twins. Their pranks and their role in the fight against Umbridge and the Death Eaters can be elaborated on in interesting ways. Also, Ginny Weasley is popular. Her growing relationship with Harry and her own strength as a witch can be explored more deeply in fan - made stories.