Scars.
Scars are awful things the Joker thinks to himself as he climbs the last few stairs of the building. "Don't fucking screw up this time" Harley says through the intercom. He sighs, knowing he will anyway no matter how hard he tries.
"You have nowhere to run Joker. Turn yourself in" The Joker laughs at Batman's statement. "Turn myself in!? You must be as insane as me." He shakes his head animatedly and edges closer to the edge of the building. Batman rushes forward and grabs him by his shirt. "If you don't turn yourself in I'll drag you to arkham like last time" The dark knight says gruffly shaking Joker slightly.
Joker pauses for a second, as if in thought, then smiles. "Hmm no!" He thrusts upward with a concealed knife which bends slightly on Batman's armor. The dark knight throws a punch with his right hand then pushes Joker to the ground. Joker laughs aloud and throws Batman to the ground "Nice playing bats but I'm out of here!" with his brief message he disappears over the edge of the building.
There has to be more to this. The Dark Knight thinks to himself sprinting to the side of the building. The Joker is no where in sight and neither is his accomplice Harley Quinn. "Wait.. No Quinn this time?" he runs back down three flights of stairs to the ground floor to check the hostages.
"THERE'S A BOMB!" A man yells. The dark knight moves quickly to disarm it, successfully rendering it useless he leads the hostages outside.
"What happened?" He asks after getting everyone situated. "That crazy guy! He.. He busted in all mad and tied me up. He told us if we stayed put we wouldn't die.
Batman muses over the information he collected then turns and vanishes into the night as sirens grow closer to the scene of the crime.