Derek (Patrick Dempsey) is back! And while we’re totally excited for Dr. McDreamy’s return to the Season 11 plot of “Grey’s Anatomy” it doesn’t seem like everyone will be thrilled with his arrival to Grey Sloan Memorial Hospital -- specifically his sister Amelia who is convinced that her big brother will be gunning for her job now that he’s no longer working on the East Coast.

Before Derek packed his bags for D.C., his position as Head of Neurology was handed over to Amelia (Caterina Scorsone) who, in our opinion, has been totally nailing it! (She did save Geena Davis’ character Dr. Herman from a fatal tumor after all.) Despite Amelia’s success, she’s still nervous that Derek may sweep the rug from under her feet and swindle the scrubs right off her back.

In a sneak peek video from episode 18, “When I Grow Up,” the Shepard siblings have an awkward encounter that takes place while Amelia is speaking with children on a class trip.

“I am the head of the department of Neuro surgery and that means I operate on brains,” she tells the kids who are completely enamored. “It’s very cool actually because I fix the big, squishy, slimy computer that runs your body!”

Derek then chimes in from out of nowhere with his two cents. “It is the coolest,” he says, forcing Dr. Webber (James Pickens Jr.) to introduce the doctor to the charmed group of touring children. But what Dr. Webber fails to mention in his summary of Derek is that in addition to being on the board and in the Neuro department he’s also Amelia’s brother -- not to mention, her employee.

“Your sister’s your boss?” one of the kids asks.

“My sister’s my boss,” he confirms.

Amelia can sense how painful it is for Derek to admit he’s working for his kid sis. But Derek insists it “rolls off the tongue.”

As fans well remember, Derek once tried to sabotage Amelia’s medical career after Owen (Kevin McKidd) got the scoop on her dark past. Owen then looked to Derek for insight, asking Amelia’s brother if she was right for the job. And can you guess what Derek said? Nothing! Absolutely nothing. He left his sister out to dry with the hope that he could snag her gig if she was fired. But eventually Derek realized just how in the wrong he was and confronted the board about his selfish slip-up.

“It’s not going to be like it was before," Derick promises in the clip. "I’m not going to angle for you job. I’m not going to steal your patients. I just want to work."

Although Amelia is appreciative of her brother coming to her defense, it doesn’t seem like she’ll ever be able to forget just how shady Derek can be when it comes to his career.

“You say that now, but I know you, Derek,” Amelia responds to her brother in the minute-long clip. “I know us. You grew up bossing me around I don’t know if this could work.”

Do you think the Shepard siblings will find a way to work together? Sound off with your theories and don’t forget to tune in to episode 18 of “Grey’s Anatomy” on Thursday, April 2, at 8 p.m. EDT on ABC.