In chapter 24, after Lee Go Seul rescues Song Jae Gu from his tormentors, she accompanies him to his job (you know, in case any 'friends' come by). The weight of his situation is becoming too much (living on his own with his younger brother and sister, being a parent to them, having to work to earn money for food and rent, and being constantly bullied) Jae Gu says that if not for his siblings, he wouldn't have the will to continue living and breaks down and cries. Unlike the stoic and serious Queen, the more rowdy Moon Young or cutsy and pushy Dal Dal, Go Seul just quietly listens to him and then gives him a comforting hug, reassuring him that he is as strong as he needs to be right now.
Queen eventually becomes a Cool Big Sis for Song Jae Gu's siblings and takes them around in her limo, showing them a good time.
While their friendship isn't exactly perfect, seeing how close and caring Queen, Moon Young, and Dal Dal become for Song Jae Gu and his siblings is very sweet.
All the interactions between Jae Gu and his siblings. They are adorable and he loves them, no matter how hard it is on him. Especially evident when he forgets to buy sausage for breakfast for his little brother and about has a breakdown over it because that's what their mother used to make them for breakfast on their birthdays. Even more heartwarming in that event was that his siblings made drawings of him telling him how much they loved him and were sorry for causing him trouble.