system
Given the following post, respond as if you're commenting on Reddit:
human
[DC] Why doesn't another hero, without the inhibitions against killing, "take care" of The Joker?
gpt
Let's assume you're one of the handful of good guys in the 'verse that *does* kill and is still allowed to operate (feasible, but rather rare).

Let's then assume that, through some fashion, you're capable of tracking the clown down (for sake of argument we'll narrow it down to Gotham, but that's still a huge city with millions of people and the Joker - theatrical and colorful though he may be - is only one of them).

When you do, let's then assume you're capable of reaching him (even Batman usually has to *react* to the Joker rather than *act*, so best of luck to you if you're kicking down doors) in a reasonable amount of time (such as during one of his televised killing sprees, which would probably be your best bet if it's some big spectacle, like bringing big balloons to the 200th anniversary parade).

So all that's done, now let's think about something else; who is...

* likely also en route
* likely *waaaay* ahead of you
* likely wearing something with a cape and pointy little ears
* likely knows you're in town and is already miffed about that
* and really, really, *really* doesn't like killing?

So there's *that* to contend with...

But most of all, think on this.  The Joker's the guy that other supervillains tell stories about when they want to scare each other.  The Joker's the guy that Lex Luthor *always* invites to his team-ups specifically because he'd rather invite his inherent chaos and deal with it internally rather than face the wrath of a jilted Clown Prince of Crime.  This is a dude with clown makeup, a purple suit, and a friggin' *flower*, and in a world where people can bend steel with their pinky fingers, wear rings that let them do almost anything, and move so fast as to be imperceptible, he is *still.  Friggin'.  Here.*

And you're gonna go and put one in his chest?  Godspeed.