Toxic Tongue

Iida is going on about respect and courtesy, and while Katsuki would usually brush him off with an insult simply out of spite, and especially out of irritation today, this time he hesitates. There's a sour taste coating his tongue, like spoiled milk, and he can feel an alarming pressure building in his stomach. Something is very wrong.----Katsuki is affected by a quirk that compels him to say horrible and hurtful things to the people around him with a side effect of vomiting a black, sludge-like substance. His day only gets worse from there.