A Force signature screamed at him. It was blaring, begging to be seen. He turned to see a young girl, not more than fourteen, running to a speeder. She hopped on it, turned it on, and flew out of the hanger at a speed that he had loved as a young man—and still did.
Vader was on Alderan checking on reports of Rebel activity. At the moment, he was in the main hanger of the palace working on his custom speeder that had been his pet project almost since he first became a Sith.
Several body guards and a scholarly man ran out of the door the young girl had just come from. They glanced around searching for the young girl. The scholar sighed and turned to the guards, "Don't tell Bail and the Queen. They have enough on their plate with these accusations without worrying about their daughter's pranks." The guards nodded and they left.
So that was the young princess. She was a prankster it seemed and flew quite well. Not only was she a prankster but she drove a TX-81. And by the sound of it, it had a B5-4I engine. That must be a sweet ride. He'd been trying to find one of those engines for ages.
An idea was forming in his mind. He put away his tools and got in his speeder. He turned it on and drove out of the hanger. He searched for the girl's Force signature. He found a faint glow of it quite a ways away. He zoomed toward it.
After several minutes he came across her. She sat at a pool, creating some flower rings. As he drew up she looked up. Her eyes hardened, "Lord Vader, to what do I owe this honor?"
He turned off the speeder and hopped out, "You have a B5-4I engine? Where on earth did you find it? I've been searching for one for ages and can't find one to save my life."
The princess's mouth dropped. She shut it and wrinkled her brow for several minutes. She tilted her head. She righted it, "I don't know anything about the Rebels if that's what you're trying to get me to tell you."
He shook his head, "No, seriously, how in the galaxy did you find that thing?"
She glared at him. She made up her mind, "An old friend of the family gave it to me for last birthday."
He shook his head again, "What I wouldn't do for a friend like that."