I love how they added the perfect amount of romance to the drama, they didn't push it, instead they added mistery to it.

The backstories where where unique and interestingly contrastring. They both came from a hard childhood, one holding a grudge, while the other is helping people from the goodness of his heart.
Giving the message to do what you can, don't linger in the past which you can't change, and live your live to the fullest

I will definitely give it a rewarch in the future !