Soohyun has an unpredictable personality, and only the persons who know her long enough, don't get surprised with what she does. In one second she's in a place quiet listening to a conversation and in the other she's dancing and singing and playing, she changes her style a lot too, like, one day she has long brown hair and in the next day she has her hair short and blond. She's the most funny person that you will ever meet, not that she tries to be funny, she just acts naturaly, being confused sometimes because of the people thinking of her as a funny person.
She's the type of person that doesn't stands to be in the same place, quiet for too long, because of that she ends up touching everything what ends up in desaster, because she she bumps into erverything and  letting fall on the ground what she had in her hands, bring, what you use to call, a very clumsy person. She's also very honest, saying everything that goes on her mind without thinking twice, what puts her in awkward situations several times. Although she's very good at keeping secrets, and make people feel confortable what makes them trust in her. She's very good at taking care of her friends, although she's always the "baby" of the group, because of her childish way of talking and being. She's also very innocent about "adult stuff", what makes some friends make fun of her because sometimes she doesn't understand what they are talking about. Of course she's well aware of the ersities of this world, its just that her mind is still a bit... like a child mind when it comes to that subject.
She loves shopping, she does that has a hobbie. She's not worried about how much she's going to spend, she's used to be treated like a princess.
Besides this childish personality, Soohyun can also be mature when she has to, behaving like a woman and not like the child that everyone knows. 

Soohyun comes from a wealthy family. Her father is a doctor as her mother, and because of that her parents weren't as presents in her life as she wished to. Her company was the maids, the nanys and her brother, Jung Daehyun (BAP). They were the wealthier family in their neighborhood, wich made some people a bit jealous and make things hard for Soohyun to gets friends in there. But she didn't mind, she had her Oppa, and everytime the would go for a walk with the nanys everyone would look at them as prince and princess, although Daehyun behavior was more mature (like a prince) than his sister, that was always playing.
One day at a party in her house she was laying near the pool, and her nany was going to get her to dinner but her mother said to let her be, because it was rare to have all the family together and she wanted to enjoy. The nany went inside and in the moment that she closed the door, Soohyun fell into the pool and hit her head in the pool border. Fortunaly her brother was near the pool and went there and took her out of the pool. After a day in the hospital to check if everything was okay, Soohyun went back home and her life went back to normal again, exept that she wasn't able to get near a pool again, and if she were a litlle more close to a pool then what she thought it was the "safe zone" she would freak out, and the only person that was able to calm her down was her brother. 

Kai is the type of guy that can be shy when he speak in public. Is really polite to his elders and tries to always look good when he is around his fans. Howhever, Kai is really playful especialy when he is with his friends. He tends to use lots of skinship with them and be really clingy.
When he is onstage he is like a y god. Everything about him screams y. When he tries to act cute, he will look like a funny guy, because he simply can´t do cute things like Tao or Sehun. He has much more iness than cuteness.
When he falls in love, he will be like a flirt with that girl and will love to a lot. will be over-protective and will be jealous easily. But if he wants he can be a real gentleman and a soft boy to her.

They are close to each other, frequently using a lot of skinship and always playing arround. Although in public they are a bit more shy, they still prefer playing arround together. But they don't just play arround, they tease each other to the point that they start fighting. Kai knows that he being with others girls and ignoring Soohyun, makes her a bit jelous, although she tries not to show that, but Kai sometimes, just to a bit he does that, but it doesn't takes long until he regrets it and goes to Soohyun, trying to please the younger girl, being a gentelmen and sweet with her, like he was "apolagizing" without words. Soohyun does that to, but with her personality, she soon gets tired of that and goes near Kai again. What they don't get is that they are falling in love with each other, and as time goes by, they will prefer even more each other company and they will fall in love even more with each other.