Klaus grinned against Regulus' skin, there against his throat where he couldn't see as he trailed his tongue over heated skin and felt the thrumming beat of his heart as he was told what it had felt like for Regulus when he'd done something like this before.
He let his teeth drag lightly over his skin there, and pressed his thigh a little more firmly between Regulus' legs hitching it up just enough to press up against him. "I'm sure he liked that too, how nice it felt for you to surrender."
Klaus pushed a hand between their bodies, letting his hand press against Regulus. More of a pressure than anything else, but he did let himself enjoy the feeling of Regulus under his hand.