Sydney Heron

Sydney Heron is a perky surgical resident at Seattle Grace Hospital.

History
She initially appeared as Bailey's substitute when Bailey was on maternity leave. She clashed with Cristina, who found Sydney's positive attitude unbearable. Cristina, at one point, even thought she was purposefully killing a patient.

In her first year, Sydney was responsible for the death of a young patient. She was given time off, and when she returned, she put a smile on her face and made everyone believe that she was alright.

After Denny died, Sydney was assigned as Izzie's peer counselor. Izzie was initially reticent, unwilling to open up to Sydney, but once Sydney confessed her own failings, Izzie was able to slightly open up. Sydney was compassionate when Izzie said that it "scared [her] too much" to discuss what had happened.

Derek Shepherd
After introducing herself to Derek Shepherd, they went out on a date. After the date, however, Sydney informed Derek that he wasn't ready for the kind of relationship she needed (much to Derek's relief who was going to let her down gently anyway), but they agreed not to let their relationship affect their work life.

Professional
She later served as Izzie's peer counselor and revealed that her perky persona actually originated from a nervous breakdown she suffered after losing a patient of her own.

Career
Dr. Sydney Heron is a surgical resident at Seattle Grace Hospital. She was in the same class year as Bailey and was in the race to be chief resident.

Unfortunately, she lost out to Callie, who was then replaced by Bailey.

Despite her excesses, Sydney has proven herself to be a competent surgeon. For example, she successfully saved the leg of a patient with Necrotizing Fasciitis, assertively defending her decision when challenged by Preston Burke.