The next thing they bought was masks. What they bought were old style hockey masks, which they pretended they wanted for some Halloween costumes they were making. But, they were not planning to keep them as is. Harry and Hermione transfigured their masks until they resembled the faces of very creepy house elves. They wanted people to fear them. It meant their victims would be more tempted to comply to their demands, ensuring they wouldn’t have to use more violence than necessary. The house elves faces would look positively alien to muggles by default – Harry and Hermione purposefully made them even creepier, making the ears longer and adding dark bags under the holes for the eyes. It was perfect.