Oh Sehun is a normal person. He has a normal job and normal friends. He is as normal, as normal gets. But twice a month, he changes. 

Into a werewolf.

He takes his wolfsbane potion and sits in his home harmlessly.

But this time, he forgets to take his potion. And he sets out for the search of his captivation, a mesmerizing scent which he has been searching for his entire life, something he hasn't been able to find uptil now.

He wants to find the person, and bite him, Oh Sehun has a fantasy. 

And when a werewolf has a fantasy, you better get the hell out of the way and let him complete it because he won't back down until he experiences it.