Ginny was nervous because this would be her first time in the presence of Lord Voldemort since her capture. She didn't know what to expect from the encounter since she had once been under the control of part of his soul. The Dark Lord had of course been told by Hermione about the story of what had happened. It was Harry being a parselmouth and how the shade of Voldemort behaved from the testimony of Harry and Ginny that had first triggered Hermione to think about the scar. Eventually, she had been able to pierce everything together and protect the Dark Lord and warn him off of killing her and ensure his immortality. 