Chara has been sparing Barnaby their presence. Just because one interaction went... some level of well, does not mean they should push their luck - they peg most of such on Frisk's presence.

So when they walk into the kitchen, they are fully prepared to just turn around and leave again as soon as they spot the golden lengths of hair. What stops them is a natural flash of their gaze to the movement of his hands, and a stilling.

They immediately doubt their judgement as they think it but... they are fairly sure those berries are nightshade. They look just like the illustrations. Had they not been from the Castle, it's doubtful Chara would have recognized them as poisonous, but with their interest, they had been looking up plants that caught their eye while gardening.

*We can't just leave!

They very much can. It's incredibly within their capabilities. They could walk out without a word, and leave him to poison himself as he pleased.

Instead, they clear their throat, back already straightened and hands clasped in front - look, no weapon. "Barnaby." They're trying not to block the door while staying close to it, which is a mild puzzle. "A moment of your time."