In this AU, Moon barely has any of their memories after Sun had basically 100% taken the virus into his AI. Their memory card is pretty corrupted. Sun and Moon still share a body, but Sun's no longer active for now. Solar was built to take Sun's place and later on learns magic to create The Newton Star for this universe. Monty is Moon's only known friend, with Lunar popping in once in a while.
this AU is a mix of SAMS and SB, so somethings are going to match up with one and some the other. Earth comes in waaay later in the story though. Also, remember, this isn't the full story, just some peaks into what's to come.