Since you joined the fatui, Tartagila, also known as Childe, has been pestering you ever since. Asking questions, taking you up on offers, etc.

You have also took a notice that he gets extremely jealous when you talk to other people, or perhaps just not being at work. You also noticed that he was a huge overthinker.

Then, you and Tartagila were out the complete a mission for the fatui, mostly finding materials for weapons.

"Ah say, isn't this a cool mineral?"