Years of experience taught her that there was no way to tell for certain that a summons from the Dark Lord would end well. Often, they didn't. She couldn't be sure how many times over the years she arrived at a summons terrified that she would never leave. Many times. Several of her fellow Death Eaters had been killed in front of her eyes for some incompetence, perceived or otherwise. Even her safety as Lord Voldemort's favorite pet didn't always keep her safe from the Cruciatus Curse or fears that she would get worse. The uncertainty was how he kept tight control over his followers.