IN THE MAKING OF WARRIOR, THEY COVERED YONGGUK IN BABY OIL TO MAKE HIM LOOK MORE MUSCLIE NEXT TO THE FIRE BUT A BIT IF HIS HAIR AND HIS EYEBROWS GOT CAUGHT ON FIRE TO AND NOW THEY ARE GONE. MOST OF THE VIDEOS HIS IN NOW, HIS EYEBROWS ARE DRAWN ONES. 

Ps. Yongguks twin is called bang yong nam and he is totally fit and looks just like Yongguk but performs in a rock band. Check it out on YouTube lol xD