Riddler's eyes went wide as Batman's hand closed around his throat. His back was literally against the wall and he had nowhere to go. Rather than putting his hand on Batman's arm in an attempt to peel him off, Edward placed his hands firmly on the wall on either side of himself. Fighting back would be useless. Batman would release him in a moment, he always did. So predictable. Like clockwork. Batman's grip tightened and Riddler smiled, tilting his head back reflexively. "You won't break your rule, Bruce. Your one rule. You don't cheat on that." he choked out. Now he raised a hand to hold Batman's arm.
Batman bared his teeth and leaned forward, placing more pressure on Riddler's windpipe. The hand Edward placed as passive defense on Bruce's arm tightened into a claw-like grip of mild panic. Batman didn't release him. "You strike my home. The only family I have. Do you still think this is a game, Nigma? Are you still so thirsty to prove yourself after you show you know everything about me by killing those I love?" Bruce growled. "Dick. Barbara. Alfred."
Edward's eyes were wide; he looked more panicked than he wished to give off. True, he'd taken a dangerous gamble in slaying the Dark Knight's most trusted and loved, certainly bolder than anything he'd done before, but you had to push limits to find limits. Right now he was hoping, a little more desperately than he'd admit to himself, that Batman's reverence for his 'one rule' would save his life. He grimaced as he tried to find enough air to speak. "Can't… Kill… Rule…" He managed.
"Your eloquence failing you, Nigma?" Batman spat. His hand tightened a little more and Edward squirmed underneath his grip. Riddler's hand clutched his arm desperately as he let out a soundless cry of fear and pain. "You're pathetic." Bruce continued. "Killing people's loved ones to prove a point." Riddler's eyes were wide and terrified and staring into Bruce's cold ones. Bruce had decided in his pursuit of Riddler that tonight would be the night his rule broke. Edward still had a pitiful kind of hope that Batman would release him and send him back to Arkham. Like always.
Riddler ran out of air to gasp for and his hand scrabbled for a solid grip on Batman's arm. his vision went red and black and fuzzy. It felt like fireworks behind his eyes. His brain was being starved of oxygen, he knew. Batman would let him go. He wouldn't die. He stared into Bruce's eyes as his vision faded. Something was different about the coldness in them. With shock, Riddler's final thought was, 'he cheated'.
Bruce could have let go after Riddler lost consciousness. Would have if it were any other time. Should have. But he didn't. He held Riddler's throat and felt his breath stop and his pulse fade and the life leave his body. He held him there a moment afterwards, staring at Riddler's dead body. He'd killed. He broke his rule. And he didn't care.