Hermione wasn’t stupid, so she had concealed her Dark Mark to anyone who wasn’t a Death Eater. Lucius and Narcissa turned a blind eye as it happened, but the look of indecision was clear on Draco’s face. Even if they hated each other, they had begrudgingly grown closer between trips to and from Malfoy Manor to speak with Voldemort and spending months together working on the cabinet. Not to mention his loathing for his Aunt was nothing short of obvious.