Grey's Anatomy has seen a lot of characters come and go, and, as a result, some amazing friendships have been struck up on the way. When Alex Karev first appeared in the pilot episode back in 2005, the character was written in late to give the show a bit of an edge, as Alex was a total jerk.

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Over time, though, Alex gradually began to mellow and became the man everyone knew he was inside. A major factor in Alex's growth was Arizona Robbins, head of Pediatric surgery, who taught Alex to be a better person and a brilliant surgeon. However,there are many reasons why these two aren't really friends.

When Alex and Arizona first met, Arizona was the new attending assigned to a young boy's case after the previous doctor died. Arizona insisted on putting the child on the transplant list as soon as possible, and she was surprised that nobody had done that already, given the state of the boy's intestines and liver.

Both Alex and Miranda Bailey didn't like Arizona's new approach, and they complained about her behind her back.Alex was bugged by Arizona's perkiness, even when they had to harvest a dying child's organs to save their own patient.

When Arizona made her Grey's Anatomy debut in season five, she and Callie Torres were immediately attracted to each other. After a slow start, they embarked on a relationship with each other, going on to become an extremely popular fan-favorite couple.

However, in the season nine finale, Arizona cheated on Callie, who was understandably devastated and angry, refusing to forgive Arizona. Arizona planned an elaborate apology, but Alex told her to just say sorry, shaming her. While Arizona's actions were questionable, you just don't shame a friend like that.

In one of season 14's funniest episodes, the majority of the surgical staff at Grey Sloan Memorial Hospital were rendered useless after Arizona was accidentally given homemade cookies laced with weed from a grateful patient. Arizonahad already handed the cookies around before she realized.

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One of the recipients of the weed cookies was Alex, who started acting high, forcing Amelia Shepherd and Owen Hunt to bring him home with them. While this was a great episode, Alex (and the other doctors) could have gotten into serious trouble all because of Arizona's mistake.

To be clear, neither Alex nor Callie cheated on Arizona, as this all took place in a flashback. In season six, the doctors attended a series of lectures given by attendings and senior members of staff, including Callie. Callie was struggling with nerves, and so Alex and Arizona encouraged her from the audience.

After a shaky start, Callie soon found her groove, and her chosen case was actually quite interesting. After encountering difficulties, Alex and Callie managed to save their patient, which led to them celebrating by having sex. Arizona didn't know about this, and so she was understandably a bit cross.

When Alex appeared in early seasons, he was a misogynistic, arrogant, hot-headed ass. Thankfully, though, he soon grew up to become a likable and trustworthy colleague. However, things soon got awkward.

In season 13, Arizona was then living with Andrew DeLuca, and they had built up quite a sweet friendship despite Arizona being DeLuca's boss. Unfortunately, due to a fatal misunderstanding, Alex saw DeLuca with Jo Wilson and severely beat him up. DeLuca had to undergo multiple surgeries, and Alex was arrested. It shouldn't have to be said, but beating up your friend's flatmate is a no go where friendship is concerned.

In season 8, Alex and all the other fifth-year residents became involved in a mad scramble in a bid to find a fellowship for next year. Alex was struggling slightly, as his project where he brought children to the hospital for surgery was over a year ago. Just when he was about to give up, he got an offer from Johns Hopkins.

They were incredibly impressed by his performance at his board exams and made him a once in a lifetime offer. Naturally, Alex considered all his options before choosing to accept the offer. However, this meant betraying Arizona who had taught him everything he knew and who was expecting him to stay with her.

Arizona and Callie's relationship was great while it lasted, but, sadly, in season 11, the two surgeons went their separate ways. Fortunately, they still remained civil towards each other and even considered them to be friends. However, when Callie announced she was moving to New York, that all went out the window.

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Callie assumed she would be taking Sofia with her, much to Arizona's horror. The couple then initiated a savage custody battle that didn't exactly paint either woman in a good light. However, Arizona needed her friends to vouch for her, and, when she asked Alex, he refused, stating he couldn't choose sides.

When Arizona found out that Alex was leaving her for Johns Hopkins, it's safe to say that she was not at all happy. In all fairness to Alex, Arizona's bad mood was not only due to his perceived betrayal; earlier that day, Arizona's late brother's childhood friend told her that he was dying.

Unable to cope with the fact that she would soon lose another part of her brother, Arizona was already on edge. When Alex told her about his decision, she snapped and took his place on the plane, as well as removing Alex from all pediatric surgeries. If it weren't for Alex, Arizona would still have her leg.

For the most part, watching Arizona's and Alex's friendship blossom over the course of ten seasons was a joy to behold. Alex learned how to be sensitive, not just with his young patients, but their parents, as well, and Arizona got a brilliant new peds surgeon.

This all went swimmingly until the dreaded plane crash occurred. If anything, the aftermath was even more brutal than the crash itself. The injured were transferred to Seattle Grace, but Arizona's infection in her leg threatened to kill her. Therefore Alex had to cut off her leg, potentially jeopardizing their friendship.

Alex and Arizona did have an amazing relationship on Grey's Anatomy, despite all their ups and downs. However, the main reason why they are not truly friends is because their relationship consists of a mentor/mentee situation.

They've never really hung out together outside of work properly, and they don't really discuss their personal lives with each other. They like each other and respect the hell out of each other, but it's mainly professional between the two. Despite this, both Arizona and Alex have had a massive impact on each other's lives, and they will always be important to one another.

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Ben Pettitt is a recent English graduate of the University of Nottingham. He loves to write, read and watch Netflix. This is one of the reasons why he decided to come and display his knowledge of pop culture as a writer for Screen Rant.

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