"A cure had to be found. Not for him," and there he sounds tired at having to clarify-- not because of Clark, just. He knows what people think, and it turns his stomach. "He infected others. Some personally, some by secreting in his blood to hospitals to be used in transfusions. We found one. We thought. It turned out to only strip the disease of the fatal element. The transformative remained."

And so what he'd said before is pieced here: the Joker was dying on (a kind of) Venom, there was a cure, but he decided to stab Bruce and laugh. Now, hopefully, it makes sense why he wanted to cure him. The original living DNA would have helped. Honestly, Bruce thinks it would have been fine to lobotomize him.

"It sent messages to the brain, triggering a complete overhaul into the 'correct' structure it was birthed with. Personality, memory, physical features. And after it sent that message it broke down into protein, nothingness, incurable because there was nothing to cure, it just was."

His voice shakes. Anger. Bruce stands up and paces, goes to the window and stares. Getting his temper back in check, or trying to.