Bara Lotus Garden

Everything.
People are not who they used to be. Places are not what they used to be. I'm not who I used to be. My view of the world and people in general changes everyday: Wavering from positive to negative, negative to positive and sometimes even somewhere in between. My entire life is changing from small steps to giant leaps or even giant steps back. My music playlist changes with each song I add to it. My stories change with each sentence I write. My thoughts and actions change with each word I hear.
Change is a constant in life, and I have learned to understand it, but I can't honestly say that I always accept it. When something changes, it is no longer what you've known, and there is fear there. Even good changes like getting a job or applying to writing contests can be scary because you don't know anything about their outcome. You know how hard you worked, and you know what effort you put in to apply, but you don't know what the outcome will be. You can guess, but you could be wrong.
This constant, yet fragmented element of life can come softly, or nearly blow you away. You can be hurt, you can be healed and you can grow. This is really the only guarantee of life. It will change. We take for granted the patterns that we're used to, and once something happens to tip that scale or shake the world you thought you knew, you can only accept it and continue on. But that isn't easy. It could take months or even years before you realize that since your world has changed, you need to change to deal with it. Even after changing you may not accept this. It's a challenge, and not always one that you are prepared for. A therapist will tell you to take your time but make sure you're progressing. A friend or family member will tell you to hurry up before the world leaves you behind. But no matter what they say, you have to look inward and decide what you can handle, and what you can practice until you get it right.
Change is difficult. Change is tough. Change is inevitable.

Because every Kdrama viewer has one.
First of all, my idea started after I read this theory online. This theory actually mentions 49 days as well, which involved a similar situation of a soul borrowing a body that is related by blood.
This is the first time I have ever heard of a savior sibling, but I think it is a plausible theory.
The Hong Sisters are known for making every detail relevant in their dramas. In My Girl, the mystery involved a cousin that was an underlying threat between the family dynamic and the relationship between Yoo Rin and Gong Chan. In You're Beautiful the mystery was Go Mi Nam and Go Min Nye's mother and Tae Hyung's mother's connection to their father. My Girl Friend is A Gumiho had an even more important mystery of how to prevent Dae-woong's death from happening in order for Mi ho to become a human.
A lot of people seem to think that Yoon Jae will die. This is possible, but considering the emotional pattern of the drama, I don't think that will happen.
Another thing about Hong Sister's dramas, the clues are always right there in front of your face. There's a reason they keep showing the book and the drawing over and over again, it plays an important role in the plot. If Yoon Jae did save Kang Kyung Joon's life in the past, there's a reason why Kang Kyung Joon is in his body now. It is a debt repaid for a life being saved.
Now, there are two theories going on about Kang Kyung Joon's body being in a coma. Either, Yoon Jae is dead, or Yoon Jae's soul is dormant in Kang Kyung Joon's body. But there's also the fact that in 49 days, two souls could exist in one body, if one soul was dormant.
I think this is the case for Yoon Jae, but not completely. Because Kang Kyung Joon and Yoon Jae are connected, it is possible that Yoon Jae is aware of what is happening with his body, but he is asleep in Kang Kyung Joon's body.
I know that a lot of people are upset that Yoon Jae will come back, but if you look at this from a writer's perspective, he has to. We have to learn the connection between Yoon Jae and Kang Kyung Joon. Whether they are siblings or donor matches, it is important to reveal the true reason behind their connection. Now it is true that Yoon Jae has not been painted as a pretty character. And even when Yoon Jae was Yoon Jae, we never saw him speak, act or react enough to discover what type of person he is. I guarantee that this was on purpose. In order to make Kang Kyung Joon appear more lively and fun, Yoon Jae has to be quiet and passive. This could be because of his role in the connection between him and Kang Kyung Joon.
All the crushes and relationships are no accident either. The foreshadowing of Gil Da Ran and Kang Kyung Joon came early in the first episode when Gil Da Ran noticed Kang Kyung Joon, but it is revealed in episode 2 that she didn't notice Yoon Jae at all. The relationship between Yoon Jae and Gil Da Ran is also a mystery because we only get bits and pieces through flash backs and Gil Da Ran's explanations that are bias in her favor. From what we have seen, I'm not convinced that Yoon Jae liked Gil Da Ran, or loved her. He cared for her, but he seemed to ask her out of guilt or duty more than anything. This is especially true if he cheated on her like the Hong Sisters are leading us to believe.
My theory is similar to Panda's, but I'm not convinced that Yoon Jae actually wanted to marry Gil Da Ran. The only characters that have expressed serious interest in her are Kang Kyung Joon and Teacher Na. Even in Gil Da Ran's colorful flash backs, Yoon Jae seems to be obligated to her but not interested.
Kang Kyung Joon will probably be Gil Da Ran's love interest in the end, but whether he is in Yoon Jae's body or his own remains a mystery. I doubt that Yoon Jae will die, but there is no doubt he will return and explain all the mysteries surrounding his proposal to Gil Da Ran, connection to Kang Kyung Joon, and decision regarding Se Young.