Obstacles

PLEASE READ CAREFULLY
This is one book, but it is split up into three different sections. Each section builds on the previous one, but it is not necessary to read all three. Each section has its own ending. This book IS a Gguktaekook book, but only in the third section. If you only like taekook or taegguk, that is in sections one and two.
Part One:
Taehyung goes to work in a palace as a butler. There are rumors that the palace is a dark place, devoid of any happiness. When he arrives at the palace, he discovers that this is because the prince is depressed, melancholy, and mourning the loss of something, but Taehyung doesn't know what. Taehyung is determined to break the prince's walls and make him happy again, but will he succeed?
Part Two:
After an attack on the castle Taehyung is whisked away through combinations of bad luck. He must make his way back to the palace, for he refuses to be the reason his prince is sad. Along the way, he meets up with another mysterious person, who looks suspiciously like his prince, who is also fighting his way towards the palace. This section is a tale of their adventures together and the obstacles they overcome to get back to their home.
Part Three:
MAJOR WARNING: The ship in this section is Gguktaekook, and I don't believe in a poly relationship when one person gets way more love than the other two, so there IS incest. A lot of it. If you are uncomfortable, I would suggest NOT reading this section. Section one and two have a storyline that ends at the end of section two, and it isn't really necessary to read the third section.
This section of the story is about finally settling into their relationship, and the obstacles they must overcome to gain acceptance from the people of the kingdom, as well as each other.

Warning:
Smut
Incest(For the incest(which is only in part three of the book and is unnecessary to read), you can just pretend that they aren't related, which makes sense given that one of the twins is literally a hybrid)