Grey's Anatomy : Addison Montgomery and Meredith Reunite for First Time Since Derek's Death

Scott Garfield/Disney Kate Walsh

Dr. Addison Montgomery is finally back in Seattle.

Kate Walsh made a triumphant return to Grey's Anatomy in Thursday night's episode — and it was definitely worth the wait.

The build-up to Addison's arrival begins at the very top of the episode, with the interns wondering in the locker room who will be leading their Grand Rounds. They quickly find out that it's none other than Addison, who makes her grand entrance by telling them, "You must be the group that's been screwing up the program."

During their rounds with Addison, Schmitt (Jake Borelli) and the other interns argue about the history between the famed neonatal surgeon and Meredith Grey (Ellen Pompeo). Longtime Grey's fans will remember that Addison was previously married to Derek Shepherd (Patrick Dempsey), and her cheating on him led to him moving to Seattle, where he of course met Meredith. The love triangle provided plenty of fodder for the early seasons of the hit ABC medical drama.

Eric McCandless/ABC

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Addison is at Grey Sloan to perform the hospital's first surgical uterine transplant and taps Schmitt to scrub in with her. When she's disappointed with some of the interns' answers while observing the surgery, Addison makes a quip referencing the baby she adopted in the final season of Private Practice in 2013, saying, "My 8-year-old listens better than these guys."

As they are mid-surgery, the hospital's air conditioning suddenly halts. Because the hospital's air filtration system is connected to the AC, Richard Webber tells Addison that she has to close her patient up as soon as possible.

Addison says she won't stop the surgery — and calls for Meredith to help quicken things up.

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Meanwhile, Meredith has been trying to tell Webber that she agreed to work part-time in Minnesota after neurosurgeon David Hamilton (Peter Gallagher) invited her to work on Parkinson's research with him there in last week's episode.

When she arrives in Addison's O.R., Meredith greets Addison amicably, despite Amelia Shepherd (Caterina Scorsone)'s concern earlier in the episode that things might be "weird" between them. The most awkward part of their reunion is when Helm (Jaicy Elliot) begins listing all of Meredith's recent accomplishments — though Meredith and Addison do banter over who will win the next Catherine Fox award.

When Meredith and Addison are finally alone in the elevator, they burst into laughter at the interns thinking there's tension between them. Suddenly, Addison breaks down into tears.

"I thought coming back here to Seattle, to Grey Sloan, that'd he'd be here," Addison says, referring to Derek, who died in season 11. "That'd I'd be able to feel that he was still here, in the city that he loved… but he isn't. And it's real. He's not here. I'm really sorry I'm doing this in front of you because you actually had to go through it."

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Meredith pauses before answering with a tear in her eye, "Addison, he is here. And he's in his children, and they are very real. And I would love for you to come and meet them."

"Meredith, you've never been one to shy away from fighting for what you love. So if you believe in fighting for this next big thing, fight for it. Richard will understand," Addison tells her.

The duo share a brief hug before snapping back apart as they leave the elevator, keeping up their charade in front of the interns.

Addison's encouragement gives Meredith the confidence to finally tell Richard her plans to split her time between Seattle and Minnesota. She agrees to stay on as chief of surgery, but tells him that she can't continue to head up the resident program.

"I think it's wrong for anyone to have that job but you," she tells him.

Grey's Anatomy airs Thursdays at 9 p.m. ET/PT on ABC.