That novel is built around the idea of a timeline reset giving the leads a brief 'extra time' to fix things, right? If so, the character who transforms most drastically in that window is definitely Seo-jin. He starts as this closed-off, almost emotionally frozen figure shaped by past trauma and corporate pressures. The extra period forces him into situations where his controlled facade cracks—seeing the fallout of his previous neglect in real time does something no amount of retrospection could. His journey from a strategic, detached partner to someone actively vulnerable, making choices based on care rather than calculation, feels earned because the clock is ticking. The limited timeframe amplifies every hesitant step he takes toward honesty.
What sells it is the contrast with the female lead, Yoo-ri. Her arc is more about reclaiming agency, but his is a foundational identity shift. We see him unlearn a lifetime of defensive habits, not just apologize. The scenes where he quietly arranges support for her family or admits his fear of loss, things he'd never have voiced before, hit harder because you know this second chance is finite. It's not about becoming perfect, but about proving change is possible even under pressure.