Seventeen-year-old Miles resents his father for suddenly moving in with his stepbrother Grant, and targets him at every turn. Grant seems gentle on the surface but secretly fights back, and the two engage in a series of prank-like battles. When Miles is bullied at school, Grant steps in, and their relationship begins to thaw. Miles discovers that Grant suffers from PTSD, carries the heavy psychological burden of believing he caused his biological father's death, and is continually emotionally abused by his birth mother, Audrey. On Grant's most vulnerable birthday, the two cross the boundary of brothers and secretly fall in love. Their sweet underground romance peaks during a graduation trip, but a private detective hired by Audrey photographs them being intimate. To protect her marriage to Clark, Audrey threatens Miles's life and forces Grant to leave; Clark also begs Grant to yield for his son's safety. Under this double pressure, Grant disappears without a word, leaving behind an everlasting rose symbolizing "eternal happiness." Miles spends long years searching and waiting, living as Grant did, yet never able to fill the void inside. Years later, during a crucial project negotiation, Grant appears in a suit as the head of the opposing company. The shock of their reunion makes Miles lose control; he throws a punch and demands answers for Grant's sudden departure. Grant holds him tightly, reveals the truth of how Audrey threatened him back then, and tells him Audrey has died of illness. With the knot in their hearts finally untied, the two cross time and pain and firmly hold each other's hands.
