There's a moment of utter panic before Frisk slips over to stand next to them, sort of holding out their arm so they could grab if they need steadying.

"Chara--" They said they might not want this! Shoulda said they really definitely wouldn't want it instead, maybe they would've listened.

If they don't stop coughing soon, Frisk'll probably resort to back patting. It's just instinct.