In Hope turned off her humanity and began to behave like her father, so it was only fitting her aunt Rebekah was the one who snapped her out of it as she was always a match for her older brother Klaus. In her exchange with her aunt Rebekah in Legacies season 4, episode 1, Hope threatened her aunt by telling her, “I am my father’s daughter, but I’m not gonna make the same mistakes.” The irony in her statement was that when Klaus was at his worst, he still held on to his humanity, and part of how he did that was his sister Rebekah.
Through Klaus had an unhealthy attachment to his sister. He constantly daggered Rebekah or murdered the men she fell in love with when he was worried she would leave him, and, on occasion, she plotted against him to get away. However, Klaus and Rebekah were essentially the same people. They were both emotional, impulsive, and desperate for love.
Legacies Clearly Hasn't Learned From Klaus' Mistakes In The OriginalsRebekah was one of very few who understood Klaus, and while the acts they often committed were anything but human, they were almost always driven by their emotions. Rebekah was Klaus’ humanity personified and part of the reason he could never let her go, and she knew this. The combination of heightened emotions and the knowledge that her brother couldn't live without her is why Rebekah could rival Klaus.
What Made Rebekah Special In The Originals
The Klaus gave Rebekah the Vampire Cure that it was clear he understood why his sister fought him for so long. In the end, Rebekah always understood that Klaus’ reckless actions stemmed from his love for her and their family, which is why she could oppose him. That knowledge gave her the power to challenge him because she knew he couldn’t live without her.
When asked in an interview in 2015 (via Elijah died with Klaus in The Originals' series finale. Rebekah, on the other hand, was just as selfish as Klaus. She wanted more out of life than her family could offer her. Elijah was patient because he had all the time in the world to complete his life goal– seeing his brother's redemption. Rebekah and Klaus, however, were prideful and driven by their thirst for love. Rebekah and Klaus would not defend a point or person they didn’t vehemently believe in, so Rebekah would often be the only one brave enough to challenge Klaus.
Rebekah’s ability to love to a fault gave her the strength to rival Klaus, and Hope is no different. Rebekah wasn’t afraid of her niece because she loved her enough to believe she wouldn’t hurt her. Legacies was just another reminder of how her empathy and love for her family gave her the ability to stare down the most powerful supernatural beings unflinchingly.