"And I don't deserve to be called a child, or told I don't take anything seriously, but that sure as fuck doesn't stop you, now does it? When you don't even know the first thing about me!" Right, so he's not exactly making his most mature arguments at the moment, but still. Arthur can't just expect him to be polite when the guy keeps making all these stupid assumptions about him. (Never mind he hasn't exactly been stellar at not jumping to conclusions.)