Sophia Bush's open marriage plotline shocks 'Grey's Anatomy' fans

Grey's Anatomy welcomed Sophia Bush to its Season 21 cast, introducing her character Dr Cass Beckman, a skilled trauma surgeon at Seattle Presbyterian Hospital. 

Bush's debut episode saw her character's chance encounter with Teddy Altman (Kim Raver) and Owen Hunt (Kevin McKidd) at an upscale restaurant.

As the evening unfolded, Teddy confided in Cass about her marital struggles with Owen, citing their demanding careers. Cass shared her unconventional solution: an open marriage with her husband, David, also a surgeon. 

"She and her husband have an open marriage, and it saved them," Bush's character revealed.

Over drinks and burgers, the two women bonded, letting loose and having "the best time" they'd had in a while. 

However, things took a surprising turn when Cass kissed Teddy, prompting Teddy to retreat, acknowledging her marriage to Owen was still "very closed."

The aftermath of the encounter played out when Teddy shared the story with Owen, expecting him to find it amusing. Instead, he stormed off, slamming the door.

Fortunately, Bush's appearance won't be a one-off. Dr. Cass Beckman will continue to recur throughout Season 21.

Bush, known for her roles in One Tree Hill, Chicago P.D., and Love, Victor, brings her expertise to the medical drama. 

Her Grey's Anatomy stint comes ahead of her reprising her iconic One Tree Hill role as Brooke Davis in the upcoming sequel series, which she'll also executive produce.