Slaves of Mordor

[Firnantoonion]

Also, Saruman doesn't seem like Sauron's slave, after all, he sent his own Mordor Orc

yes, for he knew Saruman wanted to take the ring for himself, but Saruman always believed he acted on his own, Sauron never made it clear to him that he used him, he only misguided him so saruman would do as sauron pleased.

When pippin looks in the palantir, sauron says to him that'this one is not for Saruman' Sauron wanted to question him, and he kind of ordered saruman (as he thought) to give it to him.

without the ring, Sauron could not directly slave Saruman, he could only use him to some (very far) extend. would Sauron get the Ring, saruman would become nothing more than a slave to his will.