Aria waited until he exited the floor and then jumped down from the ceiling. She made sure to trail him, but not very close. She exited the building and noticed him walking down the street, so she put headphones in, attached to nothing and made it look like she was listening to music. She trailed him, staying about 20 feet behind him at all time. 

She noticed him arrive at the barrels, not in view now. A little while back, she had gotten up to the rooftops and trailed him that way, knowing that if she followed on foot when he exited the main road, it would be obvious. She saw the rocket launcher and sighed, sending a large ball of explosive energy down, which would explode next to the barrell if he had no means to stop it.