Good- Ju Yeon is a sweet and calm girl, she is not the type of person to fight with others. She is hardworking and work on something until she succeed sometime pushing herself too hard. According to the members, Ju Yeon has the most powerful voice of the group. Being the main vocalist she learns songs really fast but she needs to pracice a lot the dance not because she can't memorise the steps but because she hasn't a good coordination in her movements that's why she needs to practice more than the others members but practice makes perfect. Being half-american and loving to cook Ju Yeon likes to cook american dishes, that she learned from her mother, to the members. She treats the members like her sisters because they are like family to her. Ju Yeon cares a lot about her fans that's why she tries to be as close to them as possible and that she tries to answer every tweet, comment or letters that her fans send to her.

Flaws- She is easily affected by criticism and insults. She is insecure and a little critic can make her doubt herself. She practices a lot because she wants to be perfect so that she won't a burden for the other members and that the group won't problems because of her. She doesn't want the other members to have problems because of her because she cares too much about them and she doesn't want to hurt them. Ju Yeon prefers being hurt or sick than hurting one of her members and sometimes that's what happen she ends losing her voice or sprain her ankle resulting of the members scolding her because she hurts herself. She is homesick sometimes.

Onstage- She doesn't talk much except when she have to and to some people that attitude might seems cold or arrogant but Ju Yeon is just shy, she is afraid to make a mistake or to say something wrong and that people will critisize her and make fun of her. She is cute but also y. When the group is interviewed Ju Yeon always appears mature, self-confident and charismatic, the only times when she is her 'true self' is at fansign where she sometimes does aegyo and where she talks to fans a lot more than she talks to MCs.

Offstage- When she is not surrended by cameras Ju Yeon is cheerful and smiles all the times. She loves to dance and sing randomly making the other members laugh. She is not afraid to say something wrong when she is with the members because she knows that they won't judge her. She post a lot of pictures or tweet on twitter and instagram because she wants to be close to her fans. 

Ju Yeon was born New York, US from korean-american parents, she learned both korean and english when she was little because her parents wanted her to speak both of theses languages. She learned to sing at the age of 6 when she started singing in her school's choir, she also learned to play violin at the age of 8. Her music teacher said about her that 'she had an angelic voice really powerful and pure'. Her music teacher encourages her to do the solo part in the choir and she accepted. She then started to do songs covers, recorded herself, sometimes she would just sing but other times she would play violin while singing, and after she posted the video on youtube  but she never showed her face because she was too shy to let the world see her. One day while listening to others songs covers she saw a video with the title 'SM Entertainment's 2008 Global Auditions - Kesha "Tik Tok" cover', Ju Yeon searched about the SM Global Auditions and she found that people could auditioned at SM Entertainment through videos whether dancing or singing videos. She decided to audition and she filmed herself showing her face for the first time. She sang SNSD's Into the new world and send it to SM Entertainment, a few days later she received an e-mail congratulating her for being accepted at SM Entertainment. So at the age of 13 she left her house and her parents to leave in Seoul, South Korea.

Her training at SM Entertainment was very tough, the trainers were really hard with her and critisized her at almost every lessons, Ju Yeon wasn't used to that kind of intense training. Ju Yeon strated to think that she didn't deserved her place in the company and that she was worthless and without talent. At that time she felt really alone, she didn't make any friends among the trainees, because the other trainees were only focus on succeeding their monthly assessment and they didn't care about making friends, and she missed her parents a lot often calling them and crying her hearts out. She felt ill at ease in the company, one time she heard one of her trainers talking about her saying that she didn't deserved being in the company and that her voice was horrible and it was torture to listen to it. After hearing that, Ju Yeon decided to leave  SM Entertainment. She talked about that with the CEO, and he was shocked to learn that she wanted to leave the company but he respected her decision. He told her to audition at Simtong Entertainment and thats what she did.

She auditioned at Simtong Entertainment in 2009. Her training at Simtong Entertainment was totally different than the one at SM Entertainment. The trainees were friendly and it felt a lot more like being with her family and friends than real work and she'd go to practice happy to go and not fearful of what the trainers would say like she was when at SM. She became friends were some girls who quickly beacame like her sisters.  She also became a close friend with Jeta because they also spent their training period together. They went through hard times and good times together and finally after 5 years of training Ju Yeon learned that she was going to debut. The first she did after hearing that good news was calling her parents and they congratulated her.  

Hoya is charismatic on stage but he is the opposite off stage. When he is with his friends Hoya is playful and a little bit childish. He is also calm and serious when he has to be. He is hardworking and wants his work to be flawless especially when it comes to dancing. Hoya is a good listener so you can talk to him when you have a problem he will always a good advice for you. He is caring, sweet and loving with his friends and family.

When he is on stage he puts on his 'y persona' thats makes fangirls hearts melt and he shows his dance killer moves. He also smiles in the cutest way ever at every occasion he gots especially in fanmeetings.

Ju Yeon and Hoya have a very close relationship. Despite Hoya often teasing Ju Yeon he deeply cares for her and he is very, a little bit too much sometimes, protective over her. They understands each others without having to talk, it's like they can read each others minds because they automatically know when the other is sad or isn't feeling well. One day, during one of the K-Strike dance lessons, Hoya came to their practice room and took Ju Yeon out of room and he hugged her, just being in his arms makes Ju Yeon feels safe and she started to cry because she was upset and tired due to their debut approaching. During the whole time when Hoya cried they didn't talked, later she had asked him how he knew that she wasn't feeling good and he answered 'I just knew you needed me'.

When it's only the both of them they like to watch tv shows while eating chocolate ice cream. Ju Yeon and Hoya loves each others but they are too afraid to confess to the other. For Ju Yeon it's because she thinks that Hoya only sees her as his little sister and for Hoya it's because he thinks that he isn't the one for her but it hurts hima nd makes him jealous when he sees her with Jeta. It is also because they are afraid to broke their friendship and they can't imagine not having the other in their lives.