I don't know why they haven't wrote a book on Darth Sidious and his life before he became senator of Naboo.

Darth Vader, the Dark Lord of the Sith, was dreaming.

In his dream, he saw his own dark form standing upon the open terrace that clung to the curved outer wall of Bast Castle, his private fortress on the planet Vjun. Freezing acidic rain pelted his helmet, and high winds tore at his black cloak with incredible fury, as if the weather itself was doing its best to kill him along with anything else that attempted to live on the barren world. And yet Vader felt more alive than he had in years.

Turning from the balcony, he entered a vaulted doorway, leaving a trail of wet bootprints on the corridor floor. The walls were lined with automated heating vents that dried his garments as he strode to the dimly illuminated observatory. Although few had ever treaded within his fortress, he was not surprised to find the young man who stood at the center of the domed-ceiling chamber.

The young man was Luke Skywalker.