Without turning his face from the rapidly approaching Willis, Lucifer turned slightly and shot his hand out to grab the top of the young man's head. [i]very[/i] firmly. "Now, now! Swearing's not nice~. More importantly, you just tried to use my Master as a shield against a supposed killer, didn't you?" The smile on his face never dropped for a second, if anything only becoming more deceptively cheerful as the light glinted off his glasses and concealed his eyes from the front. "That's no good either, is it? You're lucky that we happen to know this fine man in front of us, or there might have been a serious accident~. Of course, his companion escapes my knowledge, however." 

As the cat strengthened the grip he had on the young man's head, the sound of his voice only continued to take on an oddly sweeter tone, as if it were just a genuinely friendly reminder or fun game of some sort that he was explaining. "There are far worse things than death, you know~? But I'm sure we can work this out peacefully instead, right~?" Turning his attention fully back to Willis at his question, Lucifer opened his previously closed eyes and smiled wide. "Hello, Willis! I thought I recognized you! I came to walk Master home when this nice person showed up! By the way, that's a good question, isn't it?" He turned back to the man he still held in a vice grip, looking obliviously happy. "[i]Do[/i] I know you, Good Sir? Surely you must be a valued customer of mine or a past assistant for my research, yes? I always like to know that my acquaintances are in good health~."