Owen didn't initially think much of Cristina as a doctor. She was impersonal with her patients, hyper-competitive with her colleagues—she seemed to be in medicine to win something, and he didn't approve. But he couldn't help overhearing Derek telling Mark that she was like a single malt scotch. When Cristina confronts Owen about her father's death and why she really became a doctor, he begins to see it. He makes a few advances toward her, but when he finds her upset after fighting with Meredith, he shows her his favorite part of the hospital. It's there that we saw, literally, the steamiest kiss in Grey's history and we truly learned that "anything can happen on a vent."