Recently I've watched a lot of black Butler so that's my inspiration with this one.
Demons are put into classes, sorted by power and potential. The stronger ones are the upper class, more wealthy and looked at with more respect. The less power you have, the less opportunity and respect you receive. Luhan is at the very bottom of the barrel, but unlike the others in this position, he's there by choice. He wants people to underestimate. Sehun is of the elite higher class and when he sees a beaut like Luhan, he hires him on the spot. As a Butler.