Cristina Yang on the hit medical drama Grey's Anatomy is probably the only character in popular television history that became such a raging success despite being the heroine's friend and not a central protagonist herself. Yang was an empowered, ambitious woman and a brilliant surgeon. In short, she was everything one could hope to see in a main character.
However, like every other character in Shondaland dramas, Cristina too had her flaws. She was deeply layered, and some of the traits that made her such a great surgeon also made her a difficult human being. She was overly aloof, aggressively competitive, and even judged her best friend which led to a rift between them. Cristina might be iconic, but she is not perfect.
Worst: Too Cold And Unemotional
Cristina Yang was a near-robotic individual when she first arrived at Seattle Grace. She was often extremely cold, with terrible bedside manners when it came to patients, and didn't seem to care much for the softer emotions.
Her nature made her appear insensitive and distant, and not easily approachable at all. It was only Bailey who could keep her in line. Of course, as her storylines and character evolved, it was revealed that she was capable of profound emotions, but all of that lay underneath a layer of aloofness.
Best: No-Nonsense
Cristina's lack of attachment and no-nonsense approach to work and life helped her, especially as a doctor. In her profession, getting overly attached to patients, as Izzie did with Denny Duquette, wasn't recommended at all.
Thus, while her coldness could be seen as a bad trait, the same no-nonsense attitude was also what made her a better doctor than many.
Worst: Arrogant & Condescending
Cristina wasn't just insensitive, she was also way too arrogant to her colleagues and fellow interns. She called George O'Malley 'Bambi' which was a reference to his nervous temperament, and needless to say, the nickname didn't add to his confidence.
Cristina was also very rude to Lexie Grey at first. True, she was being a good friend to Meredith who was being just as rude to her half-sister at the time, but placing personal considerations before professional ones seemed just wrong, especially from someone like Cristina. She also treated April Kepner with great condescension simply because she didn't have the same initiative at the time.
Best: A Great 'Person'
Of course, for all her arrogance, Cristina was a very good friend to Meredith Grey. It was she who called Meredith her 'person' in the first place, a term that became as iconic as her character.
Cristina saw Meredith through a number of traumas, becoming her one confidante. She took care of her when she fell sick during her board exams, she was also deeply concerned when Meredith became seriously ill during her delivery in season 9. And it was she who reminded her that she was the sun irrespective of whether or not Derek was dreamy.
Worst: Excessively Competitive
Cristina was excessively competitive in nature and that often came in the way of her relationships at work. Her cut-throat competitive attitude did help her get to the top of her profession but it made her an extremely difficult person to deal with at times.
She would even stoop to exploiting people's sympathies after she was left at the altar by Preston Burke so that the others would simply give her the most coveted surgeries out of the goodness of their hearts. In fact, Meredith felt for her so much that she gave her the sparkle pager which Bailey had given to her. The pager's owner could simply take over a surgery that would otherwise have gone to another resident. With that pager, Cristina could get the best surgeries, thus eliminating any competition whatsoever.
Best: Ambitious
One of Cristina's best traits was her ambition to get to the top of her field and be the best surgeon that she could be. She didn't let anything or anyone come in the way of her becoming the absolute best.
True, her over-zealousness did almost get her into trouble more than once, like when she realized she had gone over the top in her oral board exams. However, she knew exactly what she wanted and went on to be one of the most brilliant surgeons of her generation.
Worst: A Terrible Mentor
Cristina couldn't have been a worse mentor if she tried. She didn't think it worth her while to even learn the names of her interns when she was a resident and had a bunch of fresh faces under her supervision.
She also started a weirdly toxic relationship with Shane Ross, which made little sense in her character's evolutionary arc. Moreover, when she found out that Lexie's batch of interns was performing surgeries on themselves so that they could learn better, she didn't take enough measures to stop it then and there, which eventually culminated in Sadie Price nearly losing her life. Cristina wasn't interested in sharing knowledge or being a good teacher. Period.
Best: Loyal & Responsible
Cristina's collaboration with Burke was highly debatable, especially when she continued to cover up for him for months, knowing well that they were lying to everyone involved, including patients, and even putting their lives at risk. However, while her decision to support Burke might have been misguided, she did it out of loyalty and love and that can never be a bad trait.
Cristina was loyal to those she truly cared for, and she was also a responsible person. She was the only one of the residents that Izzie Stevens told about her cancer diagnosis since she would be able to stay unmoved and would treat Izzie responsibly as a patient. Given her sense of responsibility, no wonder Burke considered only Yang when he thought of passing on his mantle as the director of the prestigious institute in Zurich.
Worst: Judgemental & Presumptuous
Unfortunately, towards the end of her long stint in Grey Sloan Memorial, Cristina Yang's friendship with Meredith became fraught with tension at one point. The twisted sisters nearly broke up over some of the decisions that Meredith made which Cristina clearly judged her for.
After having tried for several years, Meredith finally got pregnant and delivered baby Bailey in season 9. She then took some time to settle in as a mother and that somehow irked Cristina who judged her for 'choosing motherhood over surgery'. She wasn't against being a mom, but she had very strong opinions about whether or not Meredith should have given more importance to her family. Now, having opinions is perfectly fine, but judging a best friend for doing something she was clearly happy about isn't. Even long before that, however, when they were yet to be each other's 'person', Cristina had assumed that Meredith had been chosen for surgery since she had slept with Derek Sheperd and that she had got into the program because of her famous mother.
Best: Strength Of Character
The best trait in Cristina Yang's personality is that she has immense strength of character. Fans know that Meredith Grey has seen tremendous trauma in her life and has bounced back every time, but Cristina too has gone through some terrible experiences and has come out on top every time.
From saving Derek's life as a gunman wielded his weapon and threatened to kill everybody if she operated, to being the only one to hold on to some level of sanity and tending to everybody else during the horrific plane crash of season 8, Cristina Yang is as strong a person as one can get. One must remember she lost her father at a very early age and given the tragedies she had suffered, her failed relationships, her strength of character was admirable.