While season 12 of "Grey's Anatomy" is largely going to be about Meredith's journey as she deals with Derek's death, the other couples on the medical drama are also going to get a lot more action.

For instance, viewers will get to see more of Alex and Jo's relationship, and how Jackson and April sort out their differences and move forward in life after their son's death.

Actress Camilla Luddington had earlier sparked rumours of Alex and Jo splitting up, saying the couple has had three good seasons without major fights, and she fears there might be trouble for the couple in season 12.

"Jo and Alex had three seasons of being pretty good, which is unusual on Grey's… I just don't trust things are going to continue to go well. Because it's Grey's Anatomy," Luddington said at Comic-Con last month, according to TVLine.

However, according to Rhimes, season 12 of "Grey's Anatomy" will have a lighter tone, and we'll get to know more about Jo as a person, and Alex and Jo as a couple.

"We had a lot of stories we wanted to tell with them last season, and I promised the fans, 'We're going to tell all these Alex and Jo stories… ,'" Rhimes told the media outlet. "And then we had to take a left turn because Patrick [Dempsey] was leaving. And now we want to tell a lot of those stories — except in a lighter way. So there's a real focus on them this season."

At the same time, Jackson and April will also try to sort out their differences. The previous season ended with Jackson telling April that he wouldn't wait for her if she decided to return to the armed forces.

Although Rhimes is yet to decide what's in store for Jackson and April, she hinted at the possibility of them working out their differences and staying together.

"Because this is a lighter season, we found funny ways to tell what's a very emotional story — more of a charming way to tell an emotional story, but it is still emotional and they are still figuring it out. April is fighting for things to be better. I honestly haven't decided how it's going to turn out. I love them together, so we'll see," Rhimes told Entertainment Weekly.

Season 12 of "Grey's Anatomy" is set to return on 24 September.