childe and you were childhood friends, Childe knew you since birth basically, you're 5 years apart(you're currently 22). You were always together and all. Childe kept saying over and over again that he would marry you when you grow up.

When your second gender finally got revealed as an omega childe managed to get you alone with him in his room

"Wanna see something I learned?" He said as he asked your 6 years old self to sit on his bed "so there's this thing called a mark that will bond us forever, wanna give it a try?" He said sitting by your side your innocent self nodded and he proceeded to mark you, of course it all went wrong, childe bit down too hard which caused you to started crying and alerted both families that were in the living room taking, both parents decided it was better to keep you both apart, in the end childe's family moved out to another city and you never saw each other again and on top of that you had now a permanent mark on your neck

Several years later you were working as a waiter/waitress at a fancy restaurant you took the new customer's order to him

"Bon appetite sir, anything else just call me" you turn around to leave but the man called you back