"No," Clark says, instinctive but not easy, but then pauses, thoughtful, despite himself. He does think of Zod, inevitably, of how he doesn't have any doubt now that he'd done the right thing—had even spent too long trying not to, crucial minutes, but he can't agonise over the instinct not to kill a person. More to the point, there had been something breaking about it, in the moment. He hadn't felt grief like that since he was a teenager.

But it's complicated. Zod represented some last connection to something he didn't have, while Joker sounds like something that just severs, cleaves. Zod had been a threat to the human race, while Joker is, in the cosmic scheme of things, not such a globally looming terror. Joker is a choice, where Zod was not.

Still—

"I don't know if you should either," Clark settles on. "If it's what needs to happen, but maybe it is. Maybe you should. Either way, you're not that person who loses control. It's something that happened, but it's not who you are. And whatever happens next, whatever you decide, you're not gonna be alone with it."