Sally Underground: An AU Exploration

This AU reimagines the Sonic Underground characters within a subterranean world, drastically altering their roles, relationships, and conflicts. The setting shifts from Mobius's surface to a vast, intricate network of underground caverns, cities, and hidden civilizations. This subterranean world could be a natural formation, a lost civilization's creation, or even a secret, technologically advanced society hidden beneath the surface.

Character Adaptations:

• Sally Acorn: Instead of a princess fighting for freedom on the surface, Sally could be a skilled explorer and leader of a subterranean resistance group. Her knowledge of surface technology and tactics could be crucial in navigating the challenges of this new environment. Perhaps she's discovered a way to access the surface world, leading to conflict with those who wish to keep the underground hidden.

• Sonic, Manic, and Sonia: Their roles could remain largely the same, but their musical talents might be adapted to suit the underground setting. Perhaps their music is used to communicate across vast distances within the caverns, or to rally the resistance. The limitations of the underground environment could also present unique challenges to their speed and abilities.

• Amy Rose: Amy's role could be significantly altered. She might be a skilled geologist or cartographer, mapping the underground world and discovering hidden resources or passages. Her unwavering loyalty to Sonic could be tested by the harsh realities of this new environment.

• Tiara Boobowski: Tiara could be a member of a wealthy, technologically advanced underground family, perhaps even a rival to Sally's resistance group. Her relationship with Amy could be strained by their differing allegiances.

• Nack the Weasel: Nack could be a scavenger or a black market trader, navigating the dangerous underground world and exploiting its resources. His opportunistic nature could lead him to ally with various factions, depending on his own self-interest.

• Dr. Robotnik: Robotnik's ambitions could shift to controlling the underground's resources or technology. He might have established a hidden base within the caverns, using the underground's unique environment to his advantage. His robots could be adapted to navigate the subterranean terrain.

• King Acorn and Queen Alicia: They could be leaders of a hidden underground kingdom, facing threats from both Robotnik and internal conflicts. Their rule might be challenged by Sally's resistance group or other factions vying for power.

• King/Professor Gazebo Boobowski/Cyberooski: He could be a scientist studying the unique properties of the underground world, perhaps even discovering ancient technologies or creatures. His knowledge could be crucial to both Sally's resistance and Robotnik's ambitions.

• Amy's Parents: Their roles could be expanded to include leadership within the underground community or involvement in the conflict between Sally's group and Robotnik.

Potential Story Arcs:

• The Struggle for Resources: The underground world could be rich in valuable resources, leading to conflict between different factions.
• Exploration and Discovery: The vastness of the underground could lead to the discovery of lost civilizations, ancient technologies, or even new species.
• Political Intrigue: The underground could be a complex political landscape, with various factions vying for power.
• Technological Advancement: The underground could be home to a technologically advanced civilization, leading to conflicts over control of this technology.
• Survival Against the Odds: The harsh environment of the underground could present numerous challenges to survival.

This AU offers a wealth of possibilities for exploring themes of survival, rebellion, political intrigue, and technological advancement within a unique and compelling setting. The characters' roles and relationships could be significantly altered, leading to new conflicts and alliances. The limitations and opportunities presented by the underground environment would shape the narrative in significant ways.