One way could be through humor. For example, Amy might accidentally leave a tampon in a visible place in Sheldon's apartment and he freaks out not knowing what it is. It could create a comical scene where the other characters have to explain it to him.
Perhaps the other characters, like Penny, would be more understanding and offer Amy support. Penny could share her own experiences or just be there to comfort her. This could also be a chance for the female characters in the fanfic to bond over something that is a normal part of being a woman.
One possible plot could be Amy Rose dealing with the physical discomfort. For example, she might struggle to keep up with her usual activities like running around or fighting bad guys. She could also face some embarrassment at first if she accidentally leaks or has to deal with cramps in public. Her friends might notice her being a bit off and try to help, but not fully understand what she's going through until she explains it to them.
The plot might involve Amy Rose's search for supplies when she gets her period. In the Sonic universe, this could be an adventure in itself. She may have to venture into an unknown area to find something suitable. Along the way, she meets other female characters who help her. This not only becomes a story about her dealing with her period but also about female camaraderie and empowerment within the Sonic world.
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.
Well, it can be different in that it focuses on a very real and relatable aspect of a female character's life that is often not explored in fanfictions. Most fanfictions in the Sonic world tend to be about battles and adventures, but this one delves into a more personal and biological experience of Amy Rose.
Obviously Caroline herself is the main character. Her mother is likely to be in it as well, as mothers often play an important role in a girl's first period experience, like giving advice and support.
It could be about Caroline's initial shock and confusion when she gets her period for the first time. Maybe she's at school and has to deal with the embarrassment of not being fully prepared.
Well, it could be about Arya's confusion and discovery when she first gets her period. Maybe it shows how she copes with the physical and emotional changes, like feeling a bit scared or embarrassed at first. And how the people around her, like her mother or sister, help her understand what's going on.
There could be fanfictions where Sheldon surprises Amy with a thoughtful gesture, like creating a scientific experiment just for her to enjoy. It shows his love in his own unique way, which is very heartwarming.