Jason was traumatised. He'd been through hell and back when he fought with the Joker and nothing could ever replace that feeling of hurt he had felt. Especially not when he had seen you with Bruce, the one who abandoned him when he needed him most.
Bruce was a traitor, you were his lifeline. But seeing you with him struck something within him. If he could get his revenge, he would have to see you at some point, he knew it.
He observed you from afar from nights on end. Your smile, your laugh, the way you mope around the house. The way you used to look after him, kiss his knuckles and shake your head in disappointment if he'd come inside with his dirty boots on.
You're the woman he thought he'd love forever. Love. It was a funny concept when all he can feel now is a gaping hole in replacement of you. All that's left in it's wake is a sad shell of a man who seeks revenge.
So when he has you on the ground, his knife to your throat, he growls behind the mask, anger staining his hidden features. "What are you going to do huh?"
"I've got you!" He presses the knife firm against your skin. "Don't act surprised to see me now. You're just as bad as him."