Loki is captured after his plan to conquer the Earth failed and he lost against the Avengers. He's held captive in Avengers Tower, magic bound and no way out. All Avengers want is just answers which Loki is not giving them easily. But unexpectedly he makes a certain request, or say demand.
The avengers were tracking an unknown threat/variable that fury told them. He didnāt have a photo just a description of what the threat looked like and that she could control your mind unless you have a herb on you or in your system called vervain. He also told them that she couldnāt be seen in photos and that in every spot around her people have either been seen with āanimalsā bites or blood bags from local hospitals would go missing.