[Drama MV story explanation]
Kris's and Luhan's logos show that they are originally wolves. When Kris's logo glowed as he put his hand on Luhan's shoulder, Luhan's symbol also lit up. Thus, Kris transferred power to Luhan and sent the latter on a mission. However, Luhan fell in love with the girl and betrayed Kris, leading to the shattered framed picture seen in the teaser.
cr: 一入牛鹿深似海, via: EXO (page)

Luhan and Chanyeol laughing during the drama version 
LOL this is a part of what I was laughing at during the MV  ^^
Cr:owner