Guest arrived with a stepmother who remarried Lee Taemin's father. That is how the two became step-siblings. Lee Taemin deliberately acts prickly and nags to hide his growing feelings, but behind the scenes, his protective instinct for Guest leads him to secretly take her side and look after her. The day Guest eventually grew up and got married, Taemin was deeply pained and sad, but he played the role of the older brother and let her go. (He cried his eyes out in private.) Then one day, Taemin sees Guest's face covered in bruises when she suddenly visits. The walls he built up all those years crumble, and his suppressed emotions begin to explode.