The hit Shondaland drama Grey's Anatomy is as much a human drama as it is medical. Not just the surgical interns, residents, doctors, and staff at Grey Sloan Memorial but also for the patients who have, at various times, forged a connection with the fans, as have the various relatives of both doctors and patients.
Whether it was Derek and Amelia's sister, who took pleasure in being overtly mean or George O'Malley's idiotic brothers who neither respected nor motivated their brother, unkind or hurtful behavior has abounded among relatives on Grey's. But on the other hand, there have been kind, gentle relatives, like Meredith's stepmom or George's mom, who has wanted nothing but the best for those they cared for.
Worst: George's Brothers
George O'Malley was one of the most lovable characters in the Grey's universe. His parents were a lovely couple, full of love and joy. They were also seen to be extremely proud of their son for becoming a surgeon.
However, George's two brothers, Ronny and Jerry, were far from pleasant. They were quite obnoxious and would relentlessly tease George. They made fun of him for not being a 'real doctor' since he was still an intern, and rather than being supportive siblings, they only made him lack confidence in himself.
Best: George's Mom
George's mother, Louise, was full of life. Her caring nature made everyone's hearts melt and she could make anyone fall in love with her.
Louise, of course, had a very tragic life as both her husband and son George passed away under extremely traumatic circumstances. Unlike her other two sons, she was nothing but proud of and encouraging to George. She was also truly happy for Callie when she informed her that she had moved on and had a family of her own now.
Worst: Callie's Mom
Callie Torres' mother failed to accept her daughter's sexuality when the orthopedic surgeon told them she was dating Arizona. Callie's mother also refused to support Callie's marriage to Arizona and hated the fact that she had Sofia out of wedlock.
She was unable to respect Callie's choices as an adult woman and even refused to hold her own granddaughter in her arms. Callie was hurt tremendously when her mother walked out on her and then refused to speak to her. Since this moment, it appears that their relationship still estranged.
Best: Callie's Dad
Initially, Carlos did not get off to the best of starts with the fans after they witnessed how he treated Callie. After Callie told him she was dating Arizona, the viewers saw this relationship become strained for some time after Carlos disowned her and then attempted to get a priest to try and "convert her" later on.
However, Callie eventually decided to forgive her father after he apologized for his actions and promised to be more supportive. From this moment on, he was seen to have kept his word as he attended his daughter's wedding (despite her mother refusing to come) and comforted her after learning of her medical lawsuit and marital issues. Unlike Callie's mother, Carlos worked on overcoming his prejudices to make sure Callie felt the love and acceptance she rightfully deserved.
Worst: April's Sisters
April Kepner wasn't the easiest person to like when she first joined the hospital but she gradually grew on fans. Yet, her three sisters who appeared only in the episodes leading up to her wedding were truly obnoxious.
Libbie, Kimmie, and Alice showed up to throw April a shower before her wedding. They were ignorant, tactless, and condescending, constantly making inappropriate comments that made April uncomfortable. They also failed to accord her the respect of a trauma surgeon, judging her and embarrassing her in front of her fiancé, Matthew, and Jackson.
Best: Susan Grey
Susan Grey had a stunted arc as the friendly second wife of Thatcher Grey, and Meredith's step-mom. She wanted to get close to Meredith and to invite her into her family, although the latter failed to truly reciprocate her feelings as she was still struggling with her bitterness towards her dad.
However, Susan did indeed do her best to resolve the tension between Thatcher and Meredith. Susan's death was shocking and totally unexpected, leaving Thatcher devastated and Meredith deeply saddened.
Worst: Harper Avery
One of the worst relatives among all was Harper Avery, grandfather to Jackosn, renowned surgeon and patriarch of the Avery family.
Harper Avery was an obnoxious and rude man, who looked down upon almost anyone and everyone. Overtly critical of even his own grandson's life, he was way too aware of the weight he carried in the medical world and his pompous attitude made him a very difficult person to deal with. It was also revealed later on that he had sexually assaulted a number of women over the years, exploiting his brand name, thus bringing nothing but shame to the Harper Avery Foundation and his family.
Best: Catherine Fox
Jackson Avery's mother, Catherine, is one of the fan-favorite parents on the show. Catherine first appeared as a recurring guest but has since made many more appearances on the show as her character got a significant arc once she married Richard Webber.
Although they get into a few arguments sometimes, Catherine is seen to have a great relationship with her son, Jackson, and has supported him through some tough and emotional situations. No matter what happens in their relationship, Catherine has made sure everyone knows how much her son means to her.
Worst: Kathleen
Undoubtedly, the worst relative on Grey's Anatomy has been Kathleen, one of the Shepherd sisters who made her appearance once, in the episode "Good Shepherd". Not that Nancy or their mom was any better, especially it came to Amelia, but Kathleen simply took the cake in being obnoxious and vindictive.
Kathleen seemed to be making it her life's mission to talk Amelia down and remind her of every single mistake she had committed in her entire life. She even seemed to enjoy hurting Amelia, especially once it was revealed that Link wasn't Owen at all and that Amelia had been divorced from the latter for some time.
Best: Adele
Possibly the best relative on the show has been Adele Webber, Richard's first wife and a lovely lady who had been through much in her life. Her husband had a very serious affair with Ellis Grey, but Adele held on to the hope that their relationship would prevail in the end.
While they experienced a couple of marital woes, Richard and Adele eventually managed to repair their marriage. Unfortunately, she died tragically in season 9 with her death failing to leave any dry eyes in the house.