Armin Artlert had been stationed to guard the crystal that Annie Lyonheart had been stuck in for over a year. She had been stuck since her fight with Armin's friend, Eren Jaeger. Eren and Annie turned into titans and destroyed most of a city inside Wall Sina.
Before Annie could be captured she froze herself inside of a giant crystal. Her custody was given to the Scout Regiment. She was held in a dungeon and has been ever since.
Armin sat down and stared at her. "Why did you have to go and freeze yourself Annie? Why?" Armin said. He had always secretly cared for the blonde. Armin had just wanted to get to know her better and possibly have a relationship.
He checked the time on his watch. 10:30. Half an hour and his shift would be over. Suddenly he heard a crack. He looked up and saw a large crack on Annie's crystal. Then another crack, and another. Armin went up closer to it and the crystal shattered and Annie fell on top of him.