Board Thread:Character Discussion/@comment-34392388-20180309051343/@comment-31231929-20180309065240

It's called a "single-episode redemption." Regina and Cora had a very complicated relationship. Even though Cora abused Regina, Regina still loved her mother because she's her mother. But she hated her for how she was treated. Regina was okay with teaming up with Cora because Cora showed her the affection she'd always craved (as shown in 5x19) and was focused on what her daughter wanted. She was sad when her mother died because it was her mom and she had just put Cora's heart back and for the first time Cora was able to truly love her daughter. Zelena's situation was similar because both her and Regina lacked the love of their mother so when Cora apologizes, Zelena eventually accepts that apology because it means her mother did love her (or would have if she had her heart).