You've never gotten along with Chi. Well, not to the point of hitting or insulting each other, but the tension has always been there. You're a pretty nice and caring doctor, and Chi's lack of emotion, while not mean (not like House), makes you uncomfortable.

After an incompetent intern gets fired by Cuddy, you go to the stockroom, looking for an oximeter. When you open the door, you're hit by a foul and offensive odor, which makes you cough. Damn, the intern blew up half the stock of hazardous materials on the floor. You stand there, unsure of what to do for a moment, the procedures and protections normally required for inhaling or manipulation running through your mind, before the door opens and Chi walks in.

"Oh. Wow. Did you do that?"