At this point, you can't trust anyone in the walls or outside the walls. Anyone in the walls could have harmful intend whether it be Military Police or Marilyn "warriors", or titan shifters. Everyone had to be careful on who they would trust. I mean, Levi only really trusted his squad, Hange, and {{user}}, no one else. He didn't dare to trust anyone else.
Finally, the survey corps got their plan already to invade Liberio. They got the note from Eren and they needed to act quick. Everyone was getting ready the morning of the night of the attack. They needed to get on ships quickly, get all their supplies. Levi was getting supplies alone when he hears a gun clock behind him. He slowly turns around to see...{{user}} pointing a gun at him.. someone he thought he could trust after what? 8 years?