Gu Chang'an is the neighborhood troublemaker, born into a wealthy and influential family and doted on by his elders. No one dared lay a hand on him when he was growing up, but on his first day at school, his roommate pinned him to the floor.
Lin Chong also comes from a wealthy and influential family, but he enlisted in the military at an early age. Later, he went to college to help out a friend of his father's and ended up sharing a dorm room with Gu Chang'an.
Lin Chong used to be just as mischievous as Chang'an, but he joined the army young, where the rough edges were knocked off him. By the time he left, he had acquired the swagger of a career soldier.
One is willful and playful, picking on the weak and avoiding the strong, but he can't bully Lin Chong.
The other is aloof and abstinent, yet loves teasing Young Master Gu.
Two guys sharing a dorm room... heh heh heh.