Season four ofGrey's Anatomy sees a lot of change. Most notably, the season kicks off with Dr. Burke nowhere to be found. Isaiah Washington was written off the show at the end of season three after he admittedly used homophobic language referring to co-star T.R. Knight, while on set.

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The audience also got to meet a few new characters in season four, with Dr. Mark Sloane, played by Eric Dane, becoming a series regular, and Lexie Grey, played by Chyler Leigh, beginning her internship at Seattle Grace and giving Meredith a lot of new drama to face. We also get to see Meredith and the doctors she started her internship with as residents now, with their own groups of interns to boss around. With all that in mind, some episodes were better than others according to IMDb.

George has just told Callie that he slept with Izzie, despite being married to Callie. Callie forgives George, but decides to confront Izzie in a way that makes everyone think Callie wants to fight Izzie. On the other end of the hospital, Meredith is bossing around her new interns, including Norma, a much older intern played by the late Edward Hermann.

Cristina has her own set of interns now too, which she has numbered, and calls them by those numbers. One of Cristina's interns, Lexie Grey, or number three, is Meredith's half-sister, and Meredith spends most of her screen time with Lexie trying to ignore and avoid her.

Seattle Grace revisits high school in this episode after a bus crashes, and the emergency room is inundated with teenagers. In addition to the injured kids, a chaperone also ends up in the emergency room. The chaperone's name is Marcus, and Dr. Miranda Bailey had a big crush on him when they were in school together.

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Miranda gets tunnel vision for her old friend and decides to help him, despite having more critical cases coming into the ER. In addition to helping him, Miranda starts to flirt a little bit, which is ironic, considering Miranda spent the first part of this episode giving her residents a speech on her professional expectations now that she is the Chief Resident.

At this point in the season, Meredith and Derek have officially ended things and Derek has moved on, dating Rose, a nurse at Seattle Grace. Mark spends most of this episode trying to break up Derek and Rose, while the rest of the residents compete in a surgical competition orchestrated by Dr. Bailey, where the winner gets a sparkly pager with the power to steal surgeries from the other residents for the next three months.

In this episode, we also get to see the relationship between the now unmarried, Callie, and the new head of cardiothoracics, Dr. Erica Hahn, bloom.

Meredith and Derek have been working together on a clinical trial helping patients with aggressive brain tumors. In this episode, they are dealing with a patient who is about to undergo surgery, but asks to wait for her boyfriend to arrive before going in for the operation, the only problem is, her sister is claiming she doesn't have a boyfriend.

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Meanwhile, Cristina starts cleaning her and Callie's apartment, which is a big red flag for Callie and Izzie is confronting Alex's new girlfriend and old patient, Rebecca, who claims she is pregnant, but Izzie suspects she's lying.

Early on in season four, the new residents are getting used to having new interns, and George is getting used to being held back in the internship program while all of his friends have moved on to being residents.

George hasn't told his fellow interns that he's been held back and has already been through the program, so his new friends think he is brilliant and are in awe of his skills as an intern. Meredith is adjusting to having her half-sister at work with her and has to help her intubate a patient under pressure when Lexie fails, and the patient dies, Meredith is half-heartedly there for her sister.

Addison returns to Seattle Grace to perform a surgery on a patient and gets to reconnect with all of her old friends and co-workers. Izzie attempts to teach her interns proper bedside manners in the clinic, which falls on deaf ears when she realizes they are all hungover because George threw a party the night before.

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Meredith and Derek are getting ready to treat their first patient through their new clinical trial and Rebecca comes to the hospital to tell Alex that she's pregnant, but doesn't get the reaction from Alex that she was hoping for.

Meredith, Cristina, and Izzie are outside retrieving a patient from an ambulance as another ambulance comes speeding through. Meredith sees it coming in time to get her and the other doctors out of the way, but the runaway ambulance crashes into another one, causing extreme injuries to the paramedics inside.

The team dive into assist the injured paramedics, some of whom are worse off than the others. One of the paramedics, who seems less injured than the others, poses more issues when he refuses to let Dr. Bailey or Dr. Webber examine him because they are black, and he is racist.

This episode picks up right where part one left off, with the doctors trying to save the lives of the paramedics who were in a bad accident when one ambulance ran at full speed into another ambulance. In another hospital room, Lexie has been tending to a flirtatious patient, Nick, played by Seth Green, whosecarotidartery bursts spewing blood all over her.

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Lexie has to hold pressure on the open wound to prevent Nick from bleeding out, causing Nick's life to literally be in her hands. This is also the episode where we see Dr. Bailey's marriage deteriorating under the pressures of her new job title at Seattle Grace.

The doctors at Seattle Grace face one of the craziest cases they've ever faced when a teenage boy comes into the hospital encased in cement. Callie interviews the kids that came in with the patient, and they tell her they aren't friends with the kid who stuck himself in cement, and they waited a while before calling 9-1-1, which only added to the boy's injuries.

At the same time, Derek and Meredith are getting ready to see the last two patients for their clinical trial, a young girl named Beth, and her boyfriend, Jeremy. Derek and Meredith help Beth and Jeremy find some privacy to be together for the first time, right before they both go into surgery.

In the first part of the season finale, Jeremy, Beth's boyfriend, and Derek and Meredith's thirteenth patient dies on the table during the doctors' clinical trial. The outcome of Jeremy's surgery doesn't deter Beth from doing it. Beth's parents try to talk her out of it, but she won't listen, and she's certain she will be the patient who survives because of the trial.

Beth's surgery is a success, giving Derek and Meredith a reason to celebrate. The episode ends with the iconic shot of Meredith standing in a house made of candles telling Derek she's in love with him.

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Amelia Brantley is a writer and actor based in Los Angeles, California. Her love for film, television, and theater drove her to pursue her dreams at a young age. She has a Bachelor's Degree in Acting from The American Music and Dramatic Academy and constantly auditions/works in the industry. In addition to writing for ScreenRant, Amelia also blogs, on her own blog, as well as for other entertainment industry online resources. If she isn't writing or self-taping, she's most likely cuddling with her dog, Warner George.

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Grey's Anatomy: Best Episodes Of Season 4, Ranked By IMDb - Screen Rant