After One had called on Zero for some assistance, he didn't expect Zero to actually reply to him. This was mainly due to the fact that Zero usually only replied to Yuki and as such, it would only make sense that he wouldn't reply to anyone who tried to call on him other than his original master would get ignored. However to One's surprise, Zero really did reply and seemed to be in the mood to help One out.
"Wow, I didn't think that you would actually reply to me. It's a bit weird now since I don't know how I should be reacting. Although I do have a clear goal in mind so I might as well just get started with that," said One as he began to calm himself as he tried to come up with a reasonable request to help out Yuki as it was in both his and Zero's best interest to keep Yuki safe from all danger even if the danger was himself.