Warning: SPOILERS for Grey’s Anatomy season 18 ahead.

While Grey’s Anatomy was renewed for season 19, theories about how the long-running medical drama will conclude and what its ending holds abound. Although a time was never set on the number of seasons Grey’s Anatomy would have, the longer it goes on, the more it’s believed its end is coming sooner rather than later. With only three characters left from Grey’s Anatomy season 1 still on the show, and considering star Ellen Pompeo’s confession regarding the fact that she’s been trying to convince everyone that Grey’s Anatomy should end, it isn’t unlikely that the medical drama might end with its season 19.

It looks like Meredith has overgrown her Seattle hospital. Grey Sloan Memorial Hospital seems to have offered all it can to Meredith Grey, who grew both personally and as a surgeon inside the hospital that she described as her happy place throughout the seasons. Story-wise, that could be even seen from Meredith’s main Grey’s Anatomy season 18 storyline revolving around her splitting her time between Grey Sloan and the Grey Center in Minnesota, which offered her the chance to change the future of medicine in a way Grey Sloan never did. As she has always been the heart of Grey’s Anatomy, if even Meredith might consider leaving Grey Sloan, it truly means the medical drama has reached its natural end.

Related: Could Grey's Anatomy Really Survive Meredith Leaving?

For a show that has lasted this long, it’s reasonable for its viewers to theorize how it might end. With Grey’s Anatomy having never hesitated to kill off main characters, many have hypothesized a sad and terrible ending for Meredith Grey. Others had a more optimistic approach, suggesting an end that might feel momentous enough to be a reason why all past doctors might want to return to Grey Sloan temporarily, but not as tragic as others for protagonist Meredith Grey. Here are the most popular theories viewers have about how Grey’s Anatomy might end.

Meredith Gets Alzheimer's

Meredith Gets Alzheimer's Grey's Anatomy

The most popular Grey’s Anatomy ending theory is by far the saddest theorized, as it would have Meredith getting diagnosed with Alzheimer’s, just like her mother was at the beginning of the show. The basis for this theory is solid, as back in Grey’s Anatomy season 9, Meredith had her genome mapped for Alzheimer’s genetic markers and received positive results for more than one. While this ending would be entirely plausible, it would also be the worst possible one for a character like Meredith Grey, who viewers have seen suffer so much and whose recovery they always rooted for throughout the seasons. While it would make sense and would be cyclical as it would mirror what happened with Meredith’s mother, Ellis (Kate Burton), it would also be the cruelest ending possible, depriving Meredith of the capabilities that she cherished the most while also turning her worst nightmare into reality.

Richard Retires, Bringing Characters Back

Richard Webber retires Grey's Anatomy

A less painful theory of how Grey’s Anatomy could end involves Richard Webber (James Pickens Jr.), who is the only other character except for Meredith and Miranda Bailey (Chandra Wilson) to have been there since Grey’s Anatomy season 1. Webber covered many different roles in Grey Sloan Memorial throughout the seasons, but he was always a staple there. His retirement might be the perfect chance to end the medical drama, as Webber’s teachings were always central in Grey’s Anatomy. Additionally, because he trained multiple residents or was dear to many attendings, Webber’s retirement party would draw many of the show’s central characters who’ve left through the years, guaranteeing the perfect send-off for him and Grey’s Anatomy.

While this theory has been around for a couple of years, Grey’s Anatomy season 18 might have started setting it up. Webber’s biggest storyline in season 18 involved the Webber Method, which gave residents the chance to operate more often on patients as the surgeries would be performed by them until they reached the trickiest part of it, which they would then complete only with an attending physician present. The method backfired because Levi Schmitt (Jake Borelli) refused to wait for an attending, resulting in the patient dying and Schmitt quitting medicine, causing Webber to reevaluate his surgical abilities along with the bad call he made. While Webber only asked to undergo cognitive and physical reviews and for experts to check his judgment if they were to find him unsuitable for an OR, that alone might be enough to push him toward retirement.

Related: Grey's Anatomy S18 Finally Remembered It Knows How To Be Fun

Meredith Relocates To Minnesota For Research

Meredith Moves To Minnesota Grey's Anatomy

Grey’s Anatomy season 18 hinted at this possibility, with Meredith’s Parkinson’s trial in Minnesota being a success and David Hamilton (Peter Gallagher) extending an offer to Meredith of a permanent job at the Grey Center. While it would have been unbelievable that Meredith might have considered leaving Seattle and her family at the start of Grey’s Anatomy season 18, the Parkinson’s study led her to explore her relationship with Nick Marsh (Scott Speedman) and gave her the chance to conduct medical research that wouldn’t have been possible at Grey Sloan Memorial. Grey’s Anatomy season 18, episode 14 made this theory even more probable, with Meredith discussing the possibility of accepting the job and uprooting her family to Minnesota with Zola (Aniela Gumbs).

Zola Saves Meredith

Zola Saves Meredith Grey's Anatomy

Another popular yet sad theory on Grey’s Anatomy ending sees Zola trying to cure Meredith’s Alzheimer’s by becoming a resident at Grey Sloan Memorial Hospital. While this theory includes Meredith’s potential Alzheimer’s diagnosis, it mainly focuses on her children becoming residents at the same hospital where Meredith and her mother Ellis worked. Variations of this theory still see Meredith with Alzheimer’s and Zola choosing neurosurgery as a specialty to try and cure her mother’s illness, but also theorize that Meredith’s voiceovers heard throughout Grey’s Anatomy are readings from Meredith’s journals, which Zola will consult as Meredith did with Ellis’s journals. Yet another variation on his theory sometimes includes other doctors' children as young Grey Sloan residents, such as Sofia Robbin Sloan Torres. This suggests that Grey’s Anatomy’s series finale might use a time jump to show the original characters’ legacies, as represented by their children taking up their mantle and becoming surgeons like their parents.

Meredith Becomes Chief Of Surgery

Meredith Becomes Chief Of Surgery Grey's Anatomy

A much happier theory hypothesizes Grey’s Anatomy ending with Meredith as Chief of Surgery of Grey Sloan Memorial Hospital. While this theory wouldn’t necessarily exclude the possibility of Zola becoming a resident at Grey Sloan in the Grey’s Anatomy series finale, especially as she’s already shown interest in medicine throughout the seasons, it focuses mainly on Meredith reaching the hospital’s highest position. Grey’s Anatomy started with Meredith as a resident and showed her path to greatness and her growth as a surgeon and human being. Ending it with her giving Richard’s speech to new residents would close the circle, providing a satisfactory ending to Grey’s Anatomy that would make sense and wouldn’t be too brutal for Meredith and longtime audiences alike.

Next: Grey's Anatomy's Perfect Ending Was Set In Season 1

Grey's Anatomy releases new episodes Thursdays on ABC.