Undefined words and terms no one bothered to explain to them, dovetailing into unspoken clarifications they will not request. It would be simple enough to wrong-foot them through obfuscation, to set them off guard by forcing them to admit a weakness or a lack of foreknowledge.

"So you left him there," says Chara, flatly, extrapolating what little needs to be extrapolated. "You left him there, and made no attempt to retrieve him."

And why are they confessing this? In the spirit of honesty? Possibly to catch Chara off-guard. To what end does not matter. What matters is that it will not work.

"Well." The word drips with contempt as they stretch it out past its termination. "It's a good thing she was there to keep you safe."