Thursday's episode of ABC's "Grey's Anatomy" delved into Stephanie's backstory, and it was revealed that she was once put through a sickle cell clinical trial.

However, Jo, one of Stephanie's closest friends and the only surviving resident from their batch, betrayed Stephanie when she refused to believe the story, and instead told Amelia that Stephanie was lying.

This has strained their relationship, and it doesn't look like things will work out between them anytime soon.

Actress Jerrika Hinton, who plays Stephanie, told Variety that the upcoming episodes will explore the icy relationship these two share.

"Stephanie is completely betrayed. She revealed such a vulnerable piece of herself… Stephanie says I only tell people I trust. That's a huge bombshell for me, as a character so for her to drop this huge bombshell with Amelia who she's very close to and for her to tell Jo and for Jo to immediately not believe her, that's an outstanding betrayal. That's where the baseline of their coldness starts.

"In order for them to really earn their friendship, it's going to be icy for a while. We're going to see that play out. We're going to see what happens when the two surviving residents from our class kind of loose each other," Hinton added.

The episode titled "Old School Rock and Roll" also dropped another bombshell towards the fag end when Callie's Penny turned out to be the doctor who was attending Derek Shepherd the day he died.

Meredith is not going to have a positive reaction to Penny's presence, as she will once again be reminded of the night she lost her husband, Patrick Dempsey's Derek. The promo for Thursday's episode shows Meredith attempting to tell her guests more about Callie's girlfriend.

"Grey's Anatomy" season 12 is aired Thursdays at 8 p.m. ET on ABC. Thursday's episode is entitled "Guess Who's Coming to Dinner."

The synopsis reads:

In the midst of the sisters' dinner party, Maggie ditches her cooking duties to rush to the hospital. Meanwhile, April steps in to help cook as an attempt to avoid Jackson, and Arizona nervously waits to find out more about Callie's new girlfriend, on "Grey's Anatomy."