"There is a hole left by the loss of Meredith's best friend, and we do not try to fill it — at all," Shonda said. "That wouldn't make sense."
She's right: There can be no Cristina-replacement in Mer's life. Besides, Cristina's not dead — she's just on the other side of the world. They can always Skype, they can always visit one another. (Sandra Oh can always come back for one or two or two dozen Season 11 episodes…)
So we're back to square one regarding Geena's character! All we know is that the 58-year-old is playing a surgeon working at Grey Sloan Memorial and will appear in multiple episodes.
Based on our time living in Shondaland, her character will probably be no one we expect her to be.