Okay, since OP is blocking anyone and deleting any comment that points out the problems here, no matter how patient or generous, I'm just going to repost this, because I don't want it to get lost.
This is how I attempted to break it down for them:
"Okay so this is a series of headcanons delivered as a single piece of narrative humor. The more imprecise words you add to an idea, the easier it is to lose track of the core thought on offer.
But, condensed down, the headcanons in question seems to be as follows:
Duke gets himself into bad situations separate from his vigilante activities, and on a different tier of intensity from his peers.
Duke has no qualms with criminal activity, and casually carries firearms.
Duke is a psychopath. (Which generally I'd ignore, but the word use actually does seem to be intended to support the other headcanons, so I'll note it.)
Duke spends his civilian time partying and engaging in criminal activity.
Headcanons are generally not based in any published reality, so I'm not going to bother pointing out the numerous canon reasons that this is skewed at best.
But in absence of anything canon, I must ask, why are these your headcanons? What is it about Duke Thomas that makes it feel right to claim that he's involved in illicit activities, and has a chaotic(?) and morally dubious personal life? What about him, as a character, suggests those vibes?
"Gun tucked into his pants" is specific imagery that, especially within this context, invokes the image of a stereotypical urban gang member. Paired directly with the fact that generally speaking, suspicious packages handed to participants in organized crime are drugs or some other sort of illicit material, then the suggestion seems to be that Duke has experience in street gangs, and also with the distribution and perhaps sale of drugs.
Considering the prevalence of Bruce's "no gun" rule in relation to people who directly work with him, why do you believe Duke would have one? Why is it also an implication that these are, in your headcanon, activities he does frequently enough that he has access to firearms?
…So again…why? Why is it that this is where your mind goes? What is it about Duke Thomas that slots into this construction? Why is it also that this headcanon - that Duke is adrenaline seeking, but specifically ONLY in relation to crime - applies to the only consistently recognized Black member of the batfam?"
I usually don't give these things time an attention, I'm just tired at this point, really. But this isn't a good look. And to those who will say that this isn't serious, that it's humor, I point how how many people were excited about the idea and used it as a springboard for even more messed up, stereotypical headcanons. This stuff spreads, and it is possible, completely possible to have humor without stooping into stereotyping, that's not an excuse. These ideas are real, affect real people, and have consequences. And no one should be expected to go into a tag for a character they enjoy, and accept blatant, racist mischaracterization.
I issued a series of questions because the point is that we need to think about these things, everyone needs to be aware of the consequences of what we put out into the world, that's a general thing. We all have that responsibility. People are ignorant, people make mistakes, there's room for grace, there has to be. However, when the response to a post explaining in specific detail what was offensive and why is:
...Well, I think at that point it's pretty clear that there's no point in going out of my way to be constructive. But I don't want to forget about this, it's a great example of how anti-blackness and racism in general exists in plain sight in fandom spaces. It's exhausting, it's omnipresent and it makes engaging in community really difficult, and the last thing I or anyone else really needs is to constantly be accosted by the pain of the physical world online in supposedly liberal online spaces as well. Fandom should be an escape, but nowadays, I am considerably more likely to walk into blatant bigotry on tumblr than in real life.
That sucks and takes time and energy away from productive, enjoyable endeavors.
But after a while it just becomes unbearable to ignore this stuff. Because you can't really ignore it. You know it's there and you can watch in real time as people support it wholeheartedly.
Honestly? Makes me sad to see that the bare minimum of basic respect is too much of an ask of a lot of people.
In the future I don't think I'll bother asking at all.