1. Oh Sehun is the illegitimate son of Mr.Oh. He is not your typical highschool student but a handsome and wealthy korean heir to a large conglomeration. He is known as cold and distant towards and basically anyone else. He's mostly called "Cold Ice Guy" 

On the other hand,

Luhan is an 18-year-old Chinese boy with a mute mother and considered as ordinary. He came from a poor background. Having 3 and sometimes 4 jobs while studying is never easy for him. He thought his sister was his golden hope to reach his dreams but he was completely wrong. Unbeknowst to him, he was meant to be led in a unfaithful situation where in, without his knowledge, was the most wonderful thing that will ever happen to him.