Emperor Vader watched the security footage of his son leaving the princess's cell and smiled to himself.
Luke's frame was trembling ever so slightly—the holocams weren't able to pick the motions up but Vader could tell by the way he was walking, could see how his purposeful strides stumbled slightly, his shoulders tense. He was wracked with fine tremors: the execution of the princess was upsetting him.
Not all was well with his son, then. Luke's concerns about his own loyalties remained pertinent; Vader would send him to the ISB soon. But the mere fact that he had found the strength to confront her, and the conviction to end her manipulations permanently, boded well.
The Rebels had not damaged his son nearly so much as he had feared.
He watched the deathtroopers fall into ranks behind Luke as he exited the detention level and moved out of view of the holocams, then sat back and sighed to himself. Satisfaction was not quite the emotion he was feeling, but there was something close: a relief that he finally had his powerful, loyal son back at his side, a pleasure at the fact he could now give Palpatine's Empire to Padmé's heir, a smugness that the Rebellion, and the thorn in his side that they were, was finally crushed. He was ready to move the Empire into a new, far more effectual era—an era that would outlast the useless Republic by ten thousand years.
All would be as it should be. The galaxy would finally have its safe and secure society. And Luke would be an icon, regarded as a saviour, for making it all happen. They would rule the galaxy as father and son for as long as they lived, and they would pass on a legacy to whoever they deemed worthy thereafter.
It was their destiny.