She knew that parts of his magical core memories were built on Dark Magic. If he had learned a spell or charm in a manner that leveraged the darkness, it was near impossible to reverse the core memory and that magic would always be dark. His apparitions were a perfect example of that. She could apparate quietly, with no visible traces of magic. For him, it was violent. He snapped in and out of existence with a crack loud enough to give a person goosebumps in swirls of black smoke. All death eaters did. If the mission required stealth, he’d need to Side-Along with Harry. 