She was careful when arriving. She was not happy about this and she knew that she shouldn't do it but she threw the projectile - the batarang like thing - into the brick next to him. She was doing it to make a point. It was stained with blood... her own blood. And if Grayson didn't know it, she was going to punch him when she got close enough to him. HE had to give her one good reason not to kill him right htere... or try to - she didn't kill.