Jarvis was the master at keeping his composure. He perfected it a long time ago. It was necessary during the war, but also in his job afterward, since he so often had to deal with the oddest of requests and with the oddest of people. So when Mr. Stark Jr. fell off his stool and very dramatically came back to earth, Jarvis had no outward change in expression. He patiently waited and set the tools down, since his point was made. His methods were always proven correct in the end.
Mr. Stark Jr. talking directly to JARVIS was even more alarming than talking to the AI himself. His eyes narrowed slightly at the man, and yet again he was struck by how much he looked like his father. Howard and Jarvis always kept a strictly professional relationship to the outside world, but they were as close as brothers in truth. "Language, sir. I tried to get your attention, but I know better than to wait for a Stark." He had a very long list of stories proving just that, or the amount of times he did in fact wait until he wore down enough to get angry.
"I brought you baked goods. I thought perhaps you would appreciate them." Comfort food was not something he would say out loud, but that was its intention. He gestured to the box and glanced around, frowning. "This place needs a good cleaning. Do you have any supplies here?" Because Jarvis had every intention of putting on rubber gloves and solving that problem pretty much immediately. He might not be an employee of the Starks anymore, but he never really served Howard solely for career reasons.
"The likeness of your artificial intelligence to me is ... quite accurate. And a bit strange." The voice and intonation, for example. It was imitation for certain, and he wondered how long it took to actually program it to sound that specific.