A plot could involve Amy Rose being turned into a different form by the magic in the Black Knight's world. Sonic then has to find a way to reverse it. Along the way, they encounter various characters from the Sonic and the Black Knight game, and together they must face a new, powerful enemy that threatens the entire realm.
One idea could be Sonic having to face a new dark version of himself created by the Black Knight's magic. This dark Sonic could have different powers and a more menacing attitude, making the battles even more intense.
One idea could be a new character being introduced into the Sonic Black Knight world. This character could be from another dimension and have unique powers. They could initially be seen as a threat but end up teaming with Sonic to fight a greater evil. Another plot could be Sonic losing his sword skills and having to go through a series of challenges to regain them, all while facing off against old enemies with new twists.
Well, Amy Rose and Sonic are the central figures. Amy Rose might be the driving force in some fanfictions, as her feelings for Sonic can lead to different story arcs. Sonic is the one who usually jumps into action. Additionally, in fanfictions related to Sonic and the Black Knight, characters such as Merlina can also be significant. She has her own motives and powers, and her interactions with Amy and Sonic can add depth to the story.
One plot idea could be Lancelot training Sonic in the ways of the knights. Since Lancelot is a skilled knight, he could teach Sonic about honor, chivalry and different combat techniques. This would be interesting as Sonic's fast - paced and impulsive nature would contrast with Lancelot's more traditional and disciplined approach.
One idea could be Sonic having to face a new and more powerful dark version of the Black Knight. This would test his skills and force him to find new ways to use his speed.
One idea could be exploring Sonic's relationships with the other characters in the Black Knight universe in more depth. For example, his interactions with King Arthur and how they might change over time. Another idea is to create an alternate ending to the game's story, where Sonic makes different choices that lead to a completely new outcome. You could also write a fanfiction that delves into Sonic's thoughts and feelings during his adventures in this medieval - inspired world.
In some fanfictions, Sonic and Amy's pregnancy could be a result of a magical accident. They then have to learn how to be parents quickly. Sonic, who is used to being on the go all the time, has to slow down and be more responsible. Amy, on the other hand, is overjoyed but also a bit worried about how Sonic will adjust. They both grow closer as they prepare for the arrival of their baby.
One idea could be that Sonic and Amy face challenges in preparing for the baby while still dealing with their usual adventures. For example, Sonic might have to slow down a bit, which is really hard for him as he's always on the go. Another plot could be that their friends in the Sonic universe all come together to help them get ready, like Tails building special baby gear.
One idea could be that Amy initially sees Metal Sonic as a threat but then realizes he has some sort of glitched 'conscience' and tries to help him. For example, she might notice that he is being controlled against his will in a way and tries to free him from that control.
A plot could revolve around the mystery of who the father is, if it's not immediately obvious. This could lead to some drama and speculation among the characters. Or it could be about her journey of self - discovery during pregnancy. She might learn new things about herself, her strength, and her capacity to love. Maybe she also has to deal with changes in her relationships because of the pregnancy.