More Soulmate Marks AU stuff (a thing I will be writing later on because this is possessing me) is that Padmé and Anakin have matching marks. Palpatine sees these and fully believes that Anakin and Padmé are soulmates, especially since by the time Palpatine meets Anakin for the first time, Anakin and Padmé have already met each other, and with how taken Anakin is with Padmé, it's a safe assumption to be made.
What he doesn't know is (and what Baby Anakin doesn't mention because he at first didn't quite get the Marks either) is that while Padmé and Anakin have the same mark, they didn't fullfill each other's marks.
No, Anakin and Padmé are not soulmates.
Anakin and Rex, however, are.
When Padmé gets pregnant with the twins, it is Rex who takes her to her prenatal appointments, because if it comes down to it, they can just claim that Rex is the father. It would still cause a scandal, of course, but not as big as if people knew that the twins were Anakin's. Anakin rather likes this arrangement, because it keeps everybody off his back as well. They all know that Padmé is having an extremely healthy pregnancy, and they since finding out that it's twins, they have really put an effort into making sure that everything goes well, as Padmé is accessing all of the top-tier health care.
The thing is, that Anakin is still really, really obsessive.
He has it all planned out. He will carry out his destiny, he will end the war, he will get Rex and his brothers their freedom, and he, Padmé, Rex and the kids will live a happy life together.
He gets the dreams of Padmé dying in childbirth. They go to the doctors. The doctors run every single test and tell them that everything is absolutely as it should be, and with them all there for the birth, the chances of something happening are minimal. They will take every precaution, so if something goes wrong, they have every tool available to prevent things from escalating.
Anakin thinks that maybe the stress of the war is getting to him. But the dreams just keep coming, and they are so similar to the dreams of his mother, and he just cannot let them be.
The doctors continue to tell that everything is alright, and that they will do absolutely everything to stop anything from going wrong.
Anakin still cannot let it be. He analyses every part of his dreams, trying to see what could be the cause, trying to see the thing that connects all the dreams together-
He's never there, not in single one of the dreams. And Padmé looks so heartbroken, and she keeps asking after someone and-
There is not other option. In his dreams, Rex is dead, and Padmé keeps asking after him. She has lost her soulmate, and is heartbroken, and cannot keep going-
No, no, no. Anakin can't let that happen. He cannot lose Padmé, and he cannot lose Rex, and he cannot let Padmé lose Rex either.
If Rex is alive, then his dreams cannot come true. If Rex is there, then they cannot be real.
So Anakin becomes extremely protective of Rex, and every single battle is even more stress to him, because at least Padmé is safe on Coruscant, but Rex is not, Rex is always there, and Anakin needs to keep him safe, because if he doesn't, he will lose them both.
And he just keeps spiraling deeper and deeper, because he needs them, because losing one of them means losing the other as well, and he can't take it, he can't-
Then Palpatine offers him his help.
Anakin is so ready to listen. Palpatine is the Chancellor. He could do something, he could make it so Rex doesn't have to fight, he could make it so Anakin can have them both-
Palpatine tells him that he can help, if Anakin just helps him. And Anakin listens, listens to Palpatine tell him everything, listens to the solution he could have, and Palpatine just keeps telling how he can keep Padmé from dying.
If Rex doesn't die, if Rex is there, then Padmé won't die, either.
Palpatine keeps talking and talking and talking, and then tells Anakin of how the clones will help them destroy the Jedi, how they will be their army that brings the Empire to its fruition, and Anakin-
all Anakin hears is that Rex will have to keep fighting, that he won't have Rex, that Rex is forced to keep fighting, forced to be in more danger-
And right then and there, Anakin looks at Palpatine, and sees the enemy.