Ellen Pompeo on 'Grey's Anatomy' McDreamy surprise

"Grey's Anatomy" fans got more than they could have ever expected in the season 17 premiere: a McDreamy reunion.

At the end of the two-part premiere, a crossover event with spin-off "Station 19," Meredith Grey (Ellen Pompeo) came face-to-face with her late husband, Derek Shepherd (Patrick Dempsey), on a picturesque beach after having been found on the ground in the Grey Sloan parking lot.

The jaw-dropping moment, according to Pompeo, was a "no-brainer" because he was "one of the most important people in Meredith's life."

"What could we give our audience that would make every single audience member just so incredibly happy?" she told "Good Morning America" on Friday. "And that, clearly, was bringing Patrick Dempsey back on the show."

Pompeo said she reached out to Dempsey, whose character died at the end of season 11, and they met up to discuss the possibility of McDreamy, the nickname of Dempsey's character, returning. After realizing they had "the opportunity to bring a smile to people's faces during 2020," it was decided.

Krista Vernoff, the showrunner for "Grey's Anatomy," took to Twitter after the episode aired to share behind-the-scenes photos of the big moment and to reveal more details about just how top-secret it really was.

"Most of the actors didn’t know. Some of the writers didn’t know. Most of the good folks at the studio & network didn’t know," Vernoff tweeted.

And from the looks of the promo for next week's episode, there's more MerDer -- that's Meredith and Derek's fan-given couple name -- goodness for fans to soak up.

Editor’s Picks

'Grey’s Anatomy' star reveals which cast departures affected her most

Ellen Pompeo reveals why she stayed on 'Grey's Anatomy'

'Grey's Anatomy' star Caterina Scorsone opens up about Down syndrome and her family

Not only was it their goal to make fans feel good in a year that has been forever altered due to the COVID-19 pandemic, but Pompeo said it was her goal to "pay homage to the series as a whole" because "we don't know how much longer it's going to go."

As an homage to all the health care heroes fighting on the front lines against this novel coronavirus, this season of "Grey's Anatomy" has been dedicated to them.

"It's about empathy for me," Pompeo said of why they wanted to to pay tribute to them, adding that they are giving fans "a window into what walking in someone else's shoes looks like."

One scene from the season 17 premiere even showed Pompeo's character breaking down, completely overcome with her emotions.

"My job is to portray the human side of these doctors," she explained. "Can you imagine going to work every day and having to walk straight into a contaminated COVID ward? I mean, most people wouldn't do it."

Going back to film this season amid a pandemic meant Pompeo and her co-stars would have to undergo various protocols to keep everyone safe and healthy. This included getting tested every other day and often filming outside. This, for a cast who has largely been working together for many seasons, was a big change.

"We joke around, we play music, we dance, we play jokes on each other," she recalled of their pre-COVID days. "And all of that is kind of gone now."