Pinocchio - Song Cha Ok, the mother of the female lead, is a mendacious reporter who abandoned her daughter. Her arc is long and satisfying in every way. There is another redemption arc in this drama with a likable supporting character. But the spoiler-tagged character is one of five main roles in the drama. This character is hate-able at the beginning and both understandable and relatable at the end - the redemption is well earned, by stages. It's incredibly satisfying to watch the links of the denial chain as they break.
I see Pinocchio on your dropped list, and I encourage you to give it another try. It's super well written. I see we both gave Healer a 10, and while Pinocchio is not an action drama, it has a similar tonal range and structure - a big, spider webby plot with tendrils reaching back into the past, lots of layers, parental deaths to avenge, you know the drill.
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Oh, and also in SKY Castle, the main mom, Han Seo-jin, has kind of the redemption arc you're requesting. And some of the other moms, too, but Han Seo-jin is the most important one.
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Two Weeks is a nonstop thrill ride and riveting redemption arc for the ML Jang Tae San. I didn't entirely hate him at the beginning, but there's nothing likable about him except that he's played by Lee Joon Gi. And then exceptional circumstances explode, and he rises to the occasion. And his redemption isn't instantaneous. There's self survival battling with self sacrifice for quite a while.
