Word for someone who remains calm (and taunts) in arguments

Is there a word that describes someone who remains calm in arguments, even when the other side is extremely angry? For example, someone who smiles and replies to angry remarks? I thought of taunting, but it doesn't suit the situation I'm thinking of.

Example sentence: He was even when the English teacher yelled at him, making the teacher extremely angry.

Note: It shouldn't mean calm, but more like taunting or sneering, in a calm way.

Solution 1:

It's sort of depends on the context.

For example, my father was famous for his stoicism when my mother argued with him, which of course made her angrier and ultimately violent.

But over time the blood would drain from my father's face and his expression hardened in defiance, but we all knew he was about to lose his $hit."

But my sister would remain calm in an argument, with a sarcastic expression, is if she thought I was foolish."