Bruce strongly disagrees that it's not that dangerous. Kal-El is a kind man, he'd have to be deaf and blind to have missed that, but he's incredibly powerful and Hayley is only a girl. If he'd justifiably taken offense to her holding one of his biggest weaknesses, it could've gotten messy, fast.

But he can't harp on that, because she's revealing facts about their murderer and his stomach turns over to hear it. "So someone had his powers," he says instantly. "That's how they could-- without either of you realizing who it was." It suddenly makes a lot more sense why Hayley would want to hold onto the Kryptonite, as a pivotal weakness for the set of powers that had murdered her.

The thought makes him sober, thinking over the implications. "Thank you for telling me," he says honestly, folding his arms and drumming his fingers against his bicep. "Nothing should be impervious, for reasons like this." Bruce definitely feels better having so many people around that he knows can withstand the Hulk. "I agree that holding onto it is a good idea. We don't know what might happen again. He won't be able to guess that I have it?"

Bruce has no idea what Superman knows of his relationship with Hayley, whether he'd think to guess that she'd have passed the Kryptonite onto him.