Slytherin 2.0, after its triumphant remake following Draco's enlightenment!

The skills in question have appeal across the Houses:

Draco smiled. "Father has, um, a rather refined sense of humor, but he does understand making friends. He understands it very well. In fact he made me repeat that before I went to bed every night for the last month, 'I will make friends at Hogwarts.' When I explained everything to him and he saw that's what I was doing, he not only apologized to me but bought me an ice-cream."

Harry's jaw dropped. "You managed to spin that into an ice-cream?" Draco nodded, looking every bit as smug as the feat deserved. "Well, father knew what I was doing, of course, but he's the one who taught me how to do it, and if I grin the right way while I'm doing it, that makes it a father-son thing and then he has to buy me an ice-cream or I'll give him this sort of sad look, like I think I must have disappointed him."

Harry eyed Draco calculatingly, sensing the presence of another master. "You've gotten lessons on how to manipulate people?"

"For as far back as I can remember," Draco said proudly. "Father bought me tutors."

"Wow," Harry said. Reading Robert Cialdini's Influence: Science and Practice probably didn't stack up very high compared to that (though it was still one heck of a book). "Your dad is almost as awesome as my dad."