[Fervently.] I'm going to ask you something. Do not lie to me in this. That's an Order.
[Ciel would normally give greater care to his attire and the appearance of propriety, especially if there is a chance that an acquaintance could see him, but he's so focused on whether he can read a prevaricating lie in Sebastian's eyes that he gives any possible passersby very little thought or care.
And if Ciel isn't so shaken by what just happened and if this was anyone else besides Sebastian, Ciel would have coaxed the truth out with subtler means. But he needs the truth now, needs to know that he's not throwing in his lot with the wrong side. If Sebastian answers his question with a "yes", well...he'll have to figure out a different battle plan at that point.]
Sebastian. Did you have anything to do with my parents' death?