The Walking Dead shows that Carol (Melissa McBride) finally acknowledges her biggest mistake - her blind pursuit of revenge against Alpha (Samantha Morton) in season 10 - when she spares Keith, one of the last surviving members of the Whisperers, in the season 11 episode “Out of the Ashes.” Ever since Alpha killed Carol’s adoptive son Henry, along with 11 other Alexandrians, by placing their severed heads on pikes to indicate the boundaries of the Whisperers’ territory in season 9, Carol went down a path of vengeance that may have ultimately resulted in Alpha’s death, but brought harm to her fellow Alexandrians along the way.
Episode 5, “Out of the Ashes,” opens with Aaron having a dream about him and his daughter Gracie being stranded in the woods, surrounded by some of the past threats Aaron has faced during the apocalypse, which appears to reflect his own fear that he won’t be able to protect Gracie from the dangers of their world. Aaron then awakes to the less dramatic but very real threat of Alexandria’s instability. Walkers have once more breached Alexandria’s walls and their settlement is swiftly running out of food. With the aim of fortifying Alexandria, Aaron, Carol, Jerry, and Lydia make a trip to Hilltop to find blacksmithing tools from amongst the rubble, but instead discover a surviving member of the Whisperers. While Carol has had the most complicated relationship with the Whisperers since their introduction in season 9, her treatment of the Whisperer Keith shows that she’s finally learning from her past experiences with Alpha.
Carol's decision to save Keith shows that she considers her past pursuit of Alpha to be a mistake. Upon discovering that there are Whisperers living in Hilltop’s cellar that contributed to the destruction of Hilltop and Alexandria, Aaron threatens to unleash a walker upon Keith unless he gives up the remaining Whisperers' location. After Aaron allows the walker to bite Keith’s hand, Lydia notes that Aaron is after revenge and not information. Clearly recognizing the same vengeful streak in Aaron that she once felt towards Alpha, Carol decides to kill the walker herself and reiterates her past experiences to Aaron as a cautionary tale. “What happened to Henry and how I felt after, it controlled me. I let it take me down a very dark path. People that I care about were hurt,” says Carol. “Now everything that I do, I carry that.” By preventing Aaron from making a similar mistake motivated by revenge, Carol recognizes that the harm she did to her friends outweighed the satisfaction of Alpha’s death.
The scene in which Carol kills the walker before it can do further harm to Keith also proves that she’s learned from her error back in season 10. When Carol followed Alpha into the caves during the season 10 episode “Squeeze,” she started a cave-in when she accidentally dropped a stick of dynamite attempting to kill Alpha’s horde. The collapse of the caves not only caused Connie’s disappearance, but it brought about harmful consequences for many of the Alexandrians who were present, since Kelly lost a sister, Daryl a close friend, and Magna was traumatized by the experience of being trapped in the cave. In comparison, Carol’s choice to save Keith involved two actions she was incapable of doing before: forgiving one of the Whisperers who likely contributed to Henry’s death and putting the needs of a friend ahead of revenge.
Carol’s acknowledgement of her biggest mistake in The Walking Dead season 11, episode 5 coincidentally resolved some of its most detrimental consequences. When Aaron is interrogating the Whisperer, Carol is driven to intervene because she’s haunted by her past choices and doesn’t want Aaron to be tormented by similar regrets. After Keith thanks Carol for standing up for him, he attempts to prove to Jerry that his people are different from Alpha by informing them of Connie’s survival. In a form of poetic justice, once Carol acknowledged her mistake of revenge and helped Aaron alternatively choose forgiveness with Keith, that choice resulted in a way to fix the damage her original mistake caused, since Keith provided Carol with Connie’s last known location.