These are characters open for plotting and will on occasion appear as secondary characters in different plots.
Han Taejoon is Taeho’s younger half-brother and ten years his junior. Unlike Taeho, he does not suffer any kind of abuse from his father. In fact, the opposite is the case as Taejoon is his father’s full pride. He grows up pampered and his parents’ favorite which causes a wedge between the brothers. And although he whole-heartedly looks up to his brother, Taeho resents him, and they are never able to develop a real bond.
Taeho grows up to become quite lazy. He spends most of his youth snooping around and causes harmless trouble. Unlike his older brother, he is not studious at all and lives into his days like they are his last. Eventually, he takes up interest in mangas and tries himself in becoming a webtoon artist. For that he teams up with his best friend.
Taejoon’s fate is quite different, depending on the verse.
In verse 3, he commits suicide as his relationship with his brother only becomes worse and he cannot live with the revelation of his mother’s murder.
In verse 4, he becomes a drug addict because there is no Taeho in his life to keep him in his lane.
Oh Rain is Taeho’s half-sister and the heiress of Myungwoo COR. She is five years his junior and enjoys a good relationship with her older brother. Rain is born blind and hence lives a life sheltered from the outside world. From a young age on, she is treated with much care, like a doll
Rain is not allowed to leave the house without her assistant, Mrs. Go.
All of this has ignited a free spirit in her. Rain loves her brother’s visits because he takes her out into the real world and lets her experience it to the full extent she is capable of.
Rain’s fate is also dependant on the verse. In the verses in which her brother is not involved with her life, she is sent away into a special institution to take care of her while her parents try for an heir of the company and Taeho's second half-brother is born.
Kang Soojung is a famous opera singer theater who meets the rich heir Taeho through mutual friends. As it is initially not in her best interest to date Taeho as she has heard of the many rumors about him, she is quickly enamored by his charisma and the two of them begin to date in secret.
It is a relationship with many ups and even more downs. And although it takes a toll on Soojung, she quickly convinces herself that their relationship is just an average one.
Eventually, Soojung is confronted with the idea that Taeho might leave her and marry into an equally rich family, but she is soon surprised with his proposal. Who can say no to a prince on a white horse?
However, just as how their relationship was more rocky than sweet, even worse is their marriage. Soojung by now is well acquainted with Taeho’s many affairs and the crumbling of a picture-perfect future has sent Soojung into a spiral of alcoholism. Especially when her only option in taming him -- a pregnancy -- has only ended in a miscarriage.
Kang Soojung as for now is only part of verse 4.