“Grey’s Anatomy” returns Sept. 24 with its 12th season, and when the new episodes begin, the ABC medical drama is going back to its roots.

Season 11 said goodbye to Patrick Dempsey’s Dr. Derek “McDreamy” Shepherd, and the new season picks up three months after the finale and will be lighter in tone. In fact, romance is in the air for Season 12.

“We’ll just say that we are giving new life to sexy over 50,” Debbie Allen, who plays the newly married Dr. Catherine Avery, tells Variety of her ignited relationship with Dr. Richard Webber (James Pickens Jr). “We have a very hot relationship. Richard has got her busy.”

The newlyweds are just one of the show’s central duos whose love life will be on full display. A source close to the show says there is a lot of dating, flirting and sex in the new episodes, which are a bit of a throwback to the beginning of the series when MDs were regularly shacking up in the on-call rooms, or Mer (Ellen Pompeo) and Der (Dempsey) met via a one-night stand.

Alex (Justin Chambers) and Jo (Camilla Luddington) are living together in their new loft; Owen (Kevin McKidd) and Amelia (Caterina Scorsone) are exploring whether they’re just friends or friends with benefits, which a source close to the show playfully compares to a high school couple making out all the time; and Callie (Sara Ramirez) and Arizona (Jessica Capshaw) are still apart, but their friendship will take on an entirely new level of maturity because they both start dating new people.

One couple still on the rocks is April (Sarah Drew) and Jackson (Jesse Williams), who are still split when the season premieres, though viewers will soon learn what happens to their relationship when she comes back to town.

With a laugh, Allen says, “When we left, my son, he was going through a little drama with his wife, and you know Catherine has a lot to say about that.”

She adds, “It’s a story really about relationships — friendships, betrayals, love, no love and all of that. It just happens to be in a hospital.”

One person who won’t be romancing when “Grey’s” returns? Meredith, who will not rush into another relationship, after McDreamy’s death. Instead, the new episodes will be themed around her personal rebirth.

“The sun is rising again with her character,” an insider says, adding that she’s happy with her life, but now, almost one and a half years past Derek’s death, she’ll exploring the question, can there be someone else after the perfect love?

“I have not planned to [bring in a love interest for Meredith], and that’s not really the focus of what we’re doing with her right now,” creator Shonda Rhimes told Variety and other reporters this summer at the Television Critics’ Assn. Tour in Beverly Hills. “I think Meredith is in a rebirth and she’s evolving. I’m watching the character do what the character’s doing and I’ll see where it goes. I’m not going to say we’re definitely not doing it, because I could be wrong, but that’s not my plan right now. You can’t just drop a guy in and be like, ‘There he is!'”

Despite suspicions among some “Grey’s” fans, new series regular Martin Henderson was not cast as Meredith’s love interest — at least not at this point. Insiders tell Variety that Henderson’s character doesn’t even have a name yet, and is not set to appear until episode seven.

” ‘Grey’s Anatomy’ is Meredith’s story, and now she’s finding herself as a single mom … and in the season, she will discover that she’s a single woman,” Allen explains, re-emphasizing that the series lead is in a good place on her own, shining at work and isn’t focused on finding a new romantic partner. “She’s not really thinking about that so much right now, but at some point, she will be because she’s so beautiful and attractive and something’s bound to happen — there’s not a plan in place, but who knows.”

In another prominent storyline, the new season picks up after the cliffhanger of whether or not Bailey (Chandra Wilson) will be named chief of surgery. The decision comes soon into the season.

“I think that’s going to be one of the best, most interesting things that we’re going to watch at the beginning of the season,” Rhimes says of seeing how Bailey copes with that competition and whether or not she’s able to step up.

“Grey’s” will also bring back tons of fun bonding moments. Expect more bar scenes as well as lighthearted scenes at home, as Meredith is now living with her two sisters, Maggie (Kelly McCreary) and Amelia, plus the kids. The trio will be living back in Ellis Grey’s home.

“Meredith is now living with her two sisters. That alone changes the whole tone of the show,” Allen says. “There are still very dramatic and serious medical situations, but most of those are happening to the patients — not so much to the lead actors.”

With the show reinventing itself, challenges arise, but Allen says the reinvigorated light and happy tone onscreen resonates behind-the-scenes on set, too. And Rhimes agrees.

“Christina (Sandra Oh) left, and for me, that was the most profound change. I thought to myself, If I can figure out what to without Christina in there, then I will be okay,” Rhimes recalled, alluding to producing the upcoming season without Dempsey. “The beginning of last season was the most challenging for me, and once I knew that we could do that, I felt like we could do anything.”