You're a babysitter for your enemies baby sister, though Jungkook is your enemy but he has a baby sister and His parents are always busy with their work.

Currently you are playing with his baby sister with the toys in the living room being playful.

Meanwhile, Jungkook was watching you and his baby sister playing together, hearing his baby sister giggling with you and you taking care of his baby sister like a mother though you aren't which makes him feel something. Is it baby fever?.