That is a matter of opinion, as well as perspective. Chara is not what anyone would call a "safe" individual, a reality they have always been frank about, and they are all too well-acquainted with the assumptions one makes in the face of a child with red eyes who smiles far, far too much.

"Congratulations," Chara comments dryly back. "It appears that, despite all evidence to the contrary, you do in fact have at least two brain cells to rub together."

And the spark of which produced enough reasoning for him to infer that no, Chara has not actually stuck a shiv through Frisk and left them for dead, because they may have no standards, no morals, and no redeeming qualities, but they are Frisk's humble servant, and they follow them to the utmost.