It was automatic, it was reactionary and purely instinct at this point--Harry pushed back at Kvothe with magic, that little zap of energy to keep him from touching him. It broke their contact and then the kid was ripping off his clothes to show him his back. Harry stared, a deep nagging feeling erupting in his gut at the reminders of Justin's teachings. It soured in his stomach and for a moment he thought he'd be sick.
"No," he said. But that was all he could manage, because he decided then what he had to do. He couldn't trust the kid's words, because they lied as easily as anyone but there were things he could do that could let him read a person's character. Harry moved and made Kvothe face him, and in that second he met the boy's eyes straight on, catching him in a soulgaze.
They locked, and the moment their gaze met Harry was thrust into the inner depth's of this warlock's deepest self. What he saw sickened him, astounded him and made the bile rise in his throat. Not because the boy was dark or ugly--though those elements did exist. But he was broken. There were bodies around a campfire, the boy's family Harry knew, and the boy himself wracked with pain in the middle of it all. But glowing too with an inner determination and resolution to see it avenged. Defiant, clever, and reckless and in need of guidance.
Then it was over and Harry blinked out of the soulgaze and stepped back several paces to collect himself. You never lost the memory of a soulgaze, once it happened it stayed with you forever and Kvothe's pain painted itself across Harry's psyche and was there to stay. He kept the tears in check but his breathing was rugged for a moment as he controlled himself and let the boy re-orient his understanding too.