Greys — Anatomy - Season 12

'Grey's Anatomy' Season 12 Trailer: "Everything Has Changed"

: Their developing romance culminates in a wedding in the season finale, though Amelia initially has doubts and runs away before the ceremony. Greys Anatomy - Season 12

: 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 : 'Grey's Anatomy' Season 12 Trailer: "Everything Has Changed"

: Martin Henderson joined the cast as Dr. Nathan Riggs, whose arrival triggers a dark history for Owen Hunt involving his missing sister. Relationship Turmoil : : Martin Henderson joined the

: 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.

: Jason George (Ben Warren) was promoted to a series regular. Giacomo Gianniotti (Andrew DeLuca) also became a regular mid-season.