ABC's favorite medical drama "Grey's Anatomy" Season 12 returns on September 24 to mesmerize the fans again.

In line with this, a lot of surprising changes will happen — after Derek's demise — to the show's cast, including who makes it to series regular. Earlier, it was confirmed that Dr. Ben Warren, portrayed by Jason George, and husband to the fierce Dr. Miranda Bailey, played by Chandra Wilson, has been advanced to a regular position. Aptly so, since he has been popping out and about throughout the previous seasons. The congenial doctor, who was then an anesthesiologist, will now be coming back to Seattle from Los Angeles to be near his wife and will grab a fifth year intern spot.

According to Christian Today, George informed Tribute last June, "I'm the newest series regular on 'Grey's Anatomy.' So there you go, you are not done with me, I'm going to be around for a little bit!" 

Another rumor that has surfaced about returning cast is that of Katherine Heigl's character Izzie. Camilla Luddington has this to say when asked about it on TV Line, "It would be nuts," but added that she is "not against anything that would make for a good storyline."

Meanwhile, viewers were left hanging last season about what would happen to April and Jackson's relationship. Are they really over and done with? 

In an interview with Entertainment Weekly, Sarah Drew, who portrays the character of Dr. April Kepner, dished that Season 12 would focus more on the couple's storyline.

Drew stated, "We haven't actually broken up. We're left on the precipice. He's given me an ultimatum that gives us room to figure out what's going to happen next season. I think this is the first of many conversations. I don't see it as a total breakup, I see it as they're definitely in a really, really rough situation." (Flashback: April was left devastated by the loss of her son, Samuel, that she has found solace in returning back to the army. Although Jackson gave her a go signal, he stated that he would not be waiting for her return.)

When further asked if she can picture April living a life without Jackson, the actress replied, "No, I don't. They fought so hard for each other. Even after they got married, they fought so hard for each other as a couple as they were navigating coming from two very different backgrounds and two different world views. I can't imagine her being OK with letting go of him. I hope that we get to see them fighting for each other. I hope that's what next season brings us."

Meanwhile, another character that has suffered and left in shambles was Caterina Scorsone's character, Dr. Amelia Shepherd. Season 11 left long time followers of Meredith and Derek dumbstruck and in a state of shock when Patrick Dempsey's beloved character was killed off the hit show. It's not only Meredith who lost a husband, it's also about Amy losing the last remaining male figure in her life, her brother, who has always supported her.

Design and Trend revealed that Scorsone's reaction to Derek's death was, "I think we were all shocked, for sure. I remember ... it came in stages, like when we first heard that it was going to happen I think there was a level of shock about it, but then when we got the script and we read it, it just became so much more real."

Viewers can expect another roller coaster ride of emotions on how Meredith and the rest of the cast will move on in "Grey's Anatomy" Season 12.