The two-hour Station 19 and Grey's Anatomy crossover event premieres Thursday on ABC

After what seems like a lifetime, Grey's Anatomy and Station 19 are both back ... finally!

With the two-hour crossover event premiering Thursday at 8 p.m. ET on ABC, we needed a reminder of where we left off and what's to come — especially since the COVID-19 outbreak forced Grey's to wrap in early April, several episodes earlier than planned.

In what became the season 16 finale of Grey's, it was discovered that Richard Webber — who had been suspected to have Alzheimer's due to his recent erratic behavior — actually had cobalt poisoning from a hip replacement surgery he'd had three years ago. After recovering from a successful surgery, Richard was back to his old self and quickly remembered every last second of his wife Catherine Avery (Debbie Allen) firing him last season and then buying and shuttering Pac North hospital where he had been working just to humiliate him.

Station 19 and Grey's Anatomy
| Credit: Justin Stephens/ABC; Mike Rosenthal/ABC

Teddy (Kim Raver) and Owen's (Kevin McKidd) wedding didn't exactly go as planned, either. It's either been called off or rescheduled due to an unfortunate incident in which Owen heard his wife-to-be getting it on with her former flame Tom (Greg Germann). Yikes.

Andrew DeLuca (Giacomo Gianniotti) suffered a major meltdown after making Webber's remarkable diagnosis of cobalt poisoning — seemingly proving to Meredith Grey (Ellen Pompeo) and his sister Carina (Stefania Spampinato) that their fear that he has bipolar disorder, which runs in his family, may have merit.

Dr. Andrew DeLuca
| Credit: Raymond Liu/ABC

In an episode of Station 19 last season, while speaking about her family, Carina told girlfriend Maya, "My dad has bipolar [disorder]. And my sweet baby brother has inherited it."

"DeLuca is bipolar," Krista Vernoff, the showrunner for both Grey's and Station 19, confirmed to PEOPLE in May. "DeLuca was in a really manic state for an extended period of time. Even though he was right about the sex-trafficking victim, the way he was behaving was inconsistent with the personality we've known him to have all these years. What Carina was saying was, 'I'm worried about you. You're not yourself. You're acting like Dad.' And Meredith was saying, 'You sound like your father.' DeLuca, after finally diagnosing Richard, went from manic to depressed. That's what that last scene was when he's sitting on the floor, crying in a pit of despair after not seeing anything but high for the last several episodes."

During the Station 19 finale, "Louder Than a Bomb," Andy (Jaina Lee Ortiz) found some unexpected answers when it came to the suspicious circumstances surrounding her mother's death — and it turns out, she's still alive.

"It has been my experience in life that when it rains, it pours," Vernoff told PEOPLE of Andy's storyline. "You tend to go through a bunch of s--- at once in your evolution as human beings. We were like, 'Let's not just give Andy a little bit, let's give her a lot.' We were interested in exploring her dark and twisty-ness, the way we did with Meredith in the early years of Grey's Anatomy."

Station 19
| Credit: ABC

"We had the idea from the beginning of the season that Andy's mom was still alive and so while, yes, it is a betrayal and a shock, it is also a dream come true," Vernoff said. "It's really complex. Here's a girl who thought she was an orphan who just got a parent back … all of that is really fertile ground for us for season 4."

In addition to Andy's ongoing life developments, her new husband Robert Sullivan (Boris Kodjoe) was dealing with his own addiction struggles and painful surgery recovery. As for their relationship, time will tell.

In March, ABC released the letter from Grey's executive producers Vernoff, Debbie Allen and James D. Parriott that was sent to cast and crew announcing that "out of an abundance of caution," production on the hit series would be postponed, effective immediately, for "at least two weeks."

Two weeks later, the network announced that the Grey's Anatomy season finale — originally set to air on May 14 — would end early on April 9.

Because there were plenty of crossovers and intertwining storylines between the two shows these past seasons, Vernoff said she had to make some adjustments given the circumstances.

"I had to open up some episodes of Station 19 and had to cut some scenes and cut some dialogue that wouldn't have been satisfying without the opportunity to play it through on Grey's," she previously told PEOPLE. "I have a bunch of footage that has not yet aired, that I hope to air. I didn't want to reveal or expose those storylines on Station 19 because I'm hoping to find a way to air them in the fall on Grey's."

In a trailer for the two-hour crossover premiere, the series' two heroines — Station 19's Andy Herrera and Grey's Anatomy's Meredith Grey — take turns narrating what's to come.

"It's a war zone and we're the ones on the front line," they begin. "With all the lives in need, our world is ablaze. What we're up against now is unlike anything that came before. At times it seems like there's no end in sight. We won't stop fighting. We won't stop feeling. Because sometimes, we all need saving."

In a recent interview with Variety, Vernoff revealed that during the initial writers' room meeting in June, she didn't necessarily want to make the subject of COVID-19 a part of the show at first.

"I think that people have fatigue of COVID, and I think they turn to our show for relief," she recalled saying during the Zoom meeting.

Some were quick to disagree, though. "I think it's the biggest medical story of our lifetimes," Vernoff remembered co-executive producer Lynne E. Litt saying, noting that a real-life doctor on staff — who worked on the coronavirus frontlines while Grey's Anatomy was on hiatus — said they had a responsibility "to tell this story."

Station 19
| Credit: ABC

According to Vernoff, the season 17 premiere crossover event will take place weeks into the pandemic. The episode will also include pre-pandemic flashbacks, which will incorporate footage from the episode they were in the process of shooting when the show went on hiatus in March.

Grey's Anatomy
| Credit: ABC

She explained that in keeping with reality, the season will not feature crowded emergency and operating rooms. They're also using different camera lenses to make it seem like the actors are standing closer together than they actually are, and are writing less scenes per script, due to the new pace of shooting.

"Everything is changing," she told the outlet. "And I'm proud of what we're doing."

The two-hour crossover event premieres Thursday on ABC, with Station 19 airing at 8 p.m. ET and Grey's Anatomy airing at 9 p.m. ET.