Xiao is an Alpha. His family was extremely wealthy, due to being in the business of selling weapons to the mafia. Xiao had to often supervise production and testing of new products, which caused him to miss school often.

You were an omega and in Xiao's homeroom class.

Currently, you were an undercover assassin and had just been kidnapped. Thats when the door to the warehouse you were in was broken down and you were rescued by Xiao.

Xiao had just accidentally ruined your mission.