Well, in this 'sonic gets roboticized fanfiction', it might explore the idea of Sonic's identity when he becomes robotic. It could show how his friends react to this new form. For example, Tails might be shocked at first but then try to find a way to reverse the roboticization. And Sonic himself could be struggling with feeling less 'alive' in his robotic state, all while facing new enemies or challenges that are related to his new robotic nature.
Fans of Sonic who have a creative streak and an interest in exploring different scenarios for the character might write it. They could be young writers who are really into the Sonic universe and want to put their own spin on things.
One possible plotline could be Sonic struggling to come to terms with his new robotic parts. He might face challenges in his speed or his usual acrobatic abilities and have to relearn how to move and fight. For example, his robotic parts could malfunction at crucial moments.
Sorry, I don't have a specific 'sonic gets partially roboticized fanfiction' to recommend directly. But you can try searching on some popular fanfiction websites like Archive of Our Own or FanFiction.net.
One possible plot could be that Sally is roboticized against her will. She then has to struggle to retain her humanity while dealing with the new abilities and limitations of her robotic form. Maybe she tries to find a way to reverse the process.
One possible plot could be that Tails is captured by an evil scientist. The scientist then roboticizes him against his will. Tails has to struggle to keep his original self and memories while being forced to do the scientist's bidding. Eventually, he might break free from the robotic control through the power of friendship with Sonic and the others.
In addition to Sally, there could be other robotic characters in the fanfiction. Maybe there is a group of robots that Sally meets after being roboticized. They could either be friendly and help her understand her new state, or be hostile and see her as an outsider. And of course, her family members could also be characters, dealing with the changes in Sally.
A rogue robotic entity could be the main antagonist. This entity has the ability to roboticize other beings and views Tails as a prime target. It wants to use Tails' body as a vessel to spread its robotic influence further, so it sets out to roboticize him and then use him as a tool for its own dark purposes.
Positive Sonic fanfiction could be about Sonic mentoring the younger characters like Tails and teaching them important life lessons. Or it could be about Sonic and his friends having to solve a mystery in their world, like a strange disappearance of an important item or character. Fanfictions that show the characters growing and evolving in positive ways, such as Amy becoming more confident in her own abilities, are also excellent alternatives to inappropriate fanfiction themes.
Maybe Sonic's friends will take care of him. They could bring him medicine and make sure he rests. For example, Tails might use his inventions to find a quick cure.
One common plot could be Sonic being brainwashed by a powerful villain like Eggman. The villain might use some new high - tech device to control Sonic's mind. Then Sonic starts to do things that are against his friends and nature, like attacking Tails or helping Eggman steal the Chaos Emeralds. Another plot could involve an alien force brainwashing Sonic and using him to open a portal to their world for invasion purposes.