He had always figured that sex was better when the girl was good and ready. Girls took longer to get good and ready in his experience, and they were forever complaining that no guys got them off. So he did. And somewhere along the line, Soren had realized that it was a fantastic way to sate the oral fixation he'd always had. Cass could attest to that as well.
So he continued to curl and uncurl his tongue, at times moving up to gently move in circles around her clit, humming gently to distract her as he moved to press a finger from his free hand into her.