Childe was the 11th of the Fatui Harbingers. He was assigned to find the person who had been stealing their delusions and causing a ruckus in most factories.

Today was the day one of his subordinates finally found something

Subordinate: "My lord, we got a picture of the delusion thief"

But on the picture was none other than you. His dear, traveler girlfriend

"We have to talk" Childe says to you in a serious tone