Sidious was in the middle of a fight against half a dozen training droids. Two lightsabers spun around him at inhuman speed, blood red trails in his blurred wake. Plagueis watched him with a certain pride. His young apprentice showed himself worthy of his teachings, and – five years after the beginning of his training – he was already as powerful as his Master in the Force.
The Muun allowed himself to be lost in thoughts. Their first encounter had been made in a way that anyone could call “coincidence”, but the Sith knew better than that: the Force had decided to place the young Sheev Palpatine on his path. He had been impossible to miss.
Palpatine's past had already anchored him in the Dark Side, and Hego Damask had just to pick him like a delicate black flower. Mentally, he congratulated Cosinga Palpatine. This old fool had remarkably... how to say this?... “got the ground ready”. His relationship – or let's say his absence of relationship – with his firstborn son had been tumultuous enough that one could consider he had dug his own grave.
Plagueis allowed a smirk on his thin lips. It had been so easy to manipulate young Palpatine to commit patricide, and in the wake of it, matricide and fratricide. The young man had been so confused at the time, and had craved revenge so deeply, that it had been enough for the Sith to suggest to him some innocent-like ideas, and he had watched the soon-to-be Darth Sidious taking them and using them to avenge himself.
He had become a tieless apprentice, with no one to bring him back into the Light – he was now at his Master's mercy. Plagueis had learned how to control him, how to muzzle his pure rage, so he created in Sidious an iron-willed self-control. He had become the perfect apprentice, the perfect weapon to bring the Sith back to power.