"Yes, your destiny is here, with me and Bellatrix and the others," he affirmed.
He ran what would have been (had it not been for the polyjuice) a long bony finger up her side. "You are wanted. You'll always be wanted here. We will show you how to use your powers to do awe inspiring things."
He knew the polyjuice would be wearing off soon. "I must go now, my dear," he kissed her softly. "I'll be back next week. But you must not show Bellatrix memories of our conversation." It would be a suitable test of her occlumentic progress.