There could be a mysterious wizard. This wizard might be the one who sets the miracle in motion for Rose. He could be an old and wise figure, guiding Rose through the strange new experiences that come with the miracle.
Another possible main character could be a young boy who is also touched by the miracle that Rose gets. He and Rose could have a special connection because of it. They might discover that they are both part of a bigger prophecy related to the miracle, and together they have to face challenges and overcome evil forces that are trying to stop the positive effects of the miracle.
The fanfiction might revolve around Rose getting a miracle in the form of a special object. This object could grant her wishes or transport her to different worlds. She could then have adventures in these new places, learning about different cultures and making new friends all because of this miracle.
There could be a little fairy who is friends with the rose. The fairy could help the beast understand the language of the plants in the garden where the rose is, so that he can better communicate with the rose.
Besides Rose, there might be a family member, like her older brother who is also part of the court. He could be initially against her leaving but later comes to understand her decision. There could also be a court jester who, in his own strange way, helps Rose see the absurdity of staying in a place where the love has died. And of course, there could be servants in the court who have witnessed Rose's relationship from the sidelines and may have some insights or stories to share about what led to the love fading.
There could be the bully character. This is the one who gives Rose a hard time because of her 'teacher pet' status. They might be jealous of the attention Rose gets and try to undermine her in various ways, like spreading rumors or trying to make her look bad in front of the class.
Maybe an artist could be the main character. He is drawn to the beauty of a blooming rose and uses it as his inspiration. Through his art, he tries to capture the essence of the rose, and in the process, he discovers things about himself and the world around him.
Sonic could be a supporting character. He might be initially clueless about what's going on with Amy Rose but tries to be supportive in his own way. He could offer to do some of her tasks for her so she can rest. Tails could also be there. He might use his intelligence to find ways to ease Amy's discomfort, like inventing a device that provides heat for her cramps.
I'm not sure as I haven't read the story in detail, but there could be her family members like her parents or siblings.
Maybe her best friend, who is really brave and loyal. They have a deep bond, and the friend won't rest until Rose is safe. Her friend could be really smart and figure out the master's hiding place through some clever detective work.
Perhaps Rose is a mysterious child with a prophecy attached to her. The wizarding world is on edge about her existence, but Harry, believing in the good in people, adopts her to protect her from those who would use the prophecy for their own evil ends. He becomes her protector and mentor, guiding her through a world full of secrets and danger.
The main characters are surely the dragon and the rose. But depending on the nature of the fanfiction, there could be side characters. For instance, if it's set in a medieval - like fantasy world, there could be knights who are either trying to slay the dragon or protect the rose for some reason. Maybe there are also talking animals that serve as messengers between the dragon and the rose.