'Death Monarch…. maybe this is why you make my sister so tortured' he thought to himself
In his mind, he never could understand why Azief chose Sofia and not his sister. He did not like the guy. But he did not like feeling that his sister is not good enough for other people.
Katarina is his sister.
The sister he had protected from the hands of his father.
He is Katarina brother but sometimes he acted like her father. He gave her the love their father had never given her.
He protected her like a father
There is nothing he would not do for his sister
If there is one thing Boris wanted for her sister is for her to always be happy and never get hurt.
It is fine for him to remember all the darkness that they had to endure during their childhood. He wanted to raise her in the sun, so that she could stand under the sun happily.