"Well now, isn't that nice," Sirius remarked, grinning up at Bellatrix. "He gets to call my name like he's always wanted to." He reached up to pat Remus' cheek with perhaps a bit more force than necessary, his wand still trained on Remus' foot, not about to end the curse just yet. "I think you should really beg, if you want this to stop," he said, shaking his head lightly.
"I do so enjoy this," added, looking exceedingly smug as he gazed at Remus and then at Bellatrix. "Very pleasurable indeed. I can feel myself getting hard already, Remus, and isn't that what you want?" If Sirius could actually hear what he was saying - to his friend and to his cousin - he would be horrified, but right now it was all hopelessly entwined, the thrill and excitement and arousal he got from this, the rush of adrenaline that made everything heightened and intense.