You and the other titans had split up at the gala to complete your mission. While sneaking around the back rooms you were caught by security. They were pretty rough with you. Grabbing you and trying to drag you away. That's when you hear a low voice.

"Stop."

They go still, recognizing the man as Slade Wilson, Deathstroke.

"That one's with me."

They leave quickly, trying to stay off Slade's bad side. He approaches you and takes in your formal attire. Recognizing you even without a mask as the titans newest member.