On Thursday, ABC released the first trailer for "Grey's Anatomy" Season 12. Meredith Grey (Ellen Pompeo) warns, "You are about to find out that everything has changed."

The trailer offers a glimpse into what's in store for fans. We see the Head of Cardiothoracic Surgery Maggie Pierce (Kelly McCreary) serving a blonde mystery woman a knuckle sandwich. What's that about?

Also in the trailer, Grey is running through a hallway littered with toys in her mother's old house. She enters the living room where the late Derek Shepherd's (Patrick Dempsey) sister, Amelia Shepherd (Caterina Scorsone), is using a sledgehammer to take down a wall. It seems Amelia wants to renovate the house now that she, Grey and Pierce are residing there together.

Following the dramatic death of Derek at the end of last season, the medical drama plans to undergo a renovation as well. At the 2015 Television Critics Association summer press tour, ABC executive Paul Lee said that, while it was difficult to see Dempsey leave the show, it started a "national conversation" about what fans would like to see happen with the characters, prompting opportunities for new story lines.

"We've seen the pitch for 'Grey's Anatomy' next season. The show reinvents itself again," Lee said.

In early August, showrunner Shonda Rhimes promised fans during the TCA press tour that the new season will be more satisfying after the emotional blow of "McDreamy's" death.

"There's a much sort of lighter tone this year that we're going for. Meredith Grey has never been defined by her relationship with a man," she told a reporter.

Pompeo, also at the press tour, added that in ShondaLand, Rhimes' production company, "I don't think any female characters are ever defined by a man."

Rhimes also told the press that Derek "had to die" because with Dempsey leaving, the character either had to leave Grey for another woman, which would tarnish the memories of their 11-year relationship, or die. Showrunners chose death.

"Grey's Anatomy" returns to ABC on Thursday, Sept. 27, at 8 p.m. EDT.

Do you think Grey, Shepherd and Pierce will make good roommates? What would you like to see happen between the characters in Season 12? Share your thoughts in the comment section below.