1.Lina and Heeseung have known each other for a long time because they trained together and also appeared together at I-Land. At I-Land Lina was shy and was clingy all the time with Heeseung she would also eventually be called Heeseung's Koala bear but she is still called that and many think it's cute too. Heeseung knows a lot of things about Lina what she likes or what she doesn't like or what her character is and as far as he knows all her brothers and he actually has contact with them too but only if something would happen.
2. Lina and Heeseung also have a close relationship you can also say that you can't tear them apart that would also be confirmed by other people and members anyway the two have the same taste like playing video games, sports and eating ramen so on but that is not the only one, they are also called the ace pairs because they are on the same level. There was a moment when everyone was scared or rather the three were scared moment and why well you saw Hesseung really angry three times Lina injured herself twice and once her private things were disturbed and Heeseung didn't really like that there was trouble to the people better, because he promised her that he would always take care of her and also protect her that he would still keep
