Greys Anatomy - Season 12 -

: Alex proposes multiple times, but Jo repeatedly declines because she is secretly still married to an abusive man she fled years prior. Cast Transitions

Season 12 of Grey's Anatomy , which premiered on September 24, 2015, is often described as the "season of rebirth". Following the death of Derek Shepherd in Season 11, the show shifted to a noticeably lighter, more "rom-com" tone, reminiscent of its earliest seasons.

: The couple's marriage collapses, leading to a divorce. However, they discover April is pregnant shortly before signing the papers. Greys Anatomy - Season 12

: A bitter custody battle over their daughter, Sofia, ensues when Callie plans to move to New York with Penny.

'Grey's Anatomy' Season 12 Trailer: "Everything Has Changed" : Alex proposes multiple times, but Jo repeatedly

: Tension peaks when Callie’s new girlfriend, Penny, is revealed to be one of the doctors who failed to save Derek. Penny eventually joins the hospital as a resident, causing friction with Meredith and Amelia. Relationship Turmoil :

: Miranda Bailey successfully campaigns to become the hospital’s first female Chief of Surgery . : The couple's marriage collapses, leading to a divorce

: Meredith Grey adjusts to life as a widow, moving back into her mother's house with her "sisters," Maggie Pierce and Amelia Shepherd. A major mid-season arc involves Meredith being brutally attacked by a patient, leading to a long recovery and therapy.