I recently did an interview (will post when it's ready) about the work I do, and the question about problematic players came in, specifically the issue of murder hobos. For those who don't know, a murder hobo refers to a player character who is effectively a sociopathic murderer who serves only to kill, screw, or loot everything that they can. This is a very common trap that a lot of DMs fall into, often by not giving their players enough focus.
In teacher training, one of the things we're taught is to keep the highly capable kids engaged with more difficult subject matter, otherwise they get bored and turn destructive. (An aside, same goes with Border Collies- I grew up with several, and if you don't give them a job they will eat your couch.) Think of your players as a highly capable student with a sword. The framing of the game gives your players access to highly lethal tools, and very often it turns into a scenario where, if all you have is a hammer, everything looks like a nail.
So the end result is campaigns where the DM had ideas of where the plot should go, and the players probably didn't want to kill that shopkeeper, half the town guards, and be forced to move to the next town to do it all again, but that's how things played out. This is especially exacerbated by 'chaotic neutral' characters who conflate the CN alignment with absolutely evil behavior, oft using the excuse, 'Oh, but I'm chaotic neutral, I'm unpredictable, I'm just playing my alignment' when they are chaotic evil, they are completely predictable, and they are not playing their alignment well at all.
Very often murder hobos also arise from some issues with the players themselves. The idea that D&D is a blank canvas for you to play GTA rather than a social, constructive game is rooted in some pretty selfish, toxic ideas, and nearly every murder hobo I've encountered has been a guy who is embracing toxic masculinity through their gameplay- They want to show off what a powerful fighter they are by killing the weak, ignoring the other players wishes for a constructive, good aligned team, and would rather derail the campaign and frustrate the DM- they find it funny when that happens. (Note that there's a difference in doing something unexpected that takes the DM by surprise and doing something dickish that stomps all over the DM's world. One is a pleasant surprise, one is just a dick move.)
So, in my game, I work with a lot of young men, many of which have a lot of anger and would be prime candidates to create murder hobo characters. And I have had kids lean that way. However, there's two ways I've found to resolve it.
The first is natural consequences. A player decides to go attack a guard? That's fine, the guard is ridiculously high level, or has some very strong enchanted armor, and the player that decided to attack the guard is instantly knocked out and has to spend a while in prison while the rest of the players have to scrounge enough money to bail him out. While they may decry this as railroading, it's important to show that you're fine with improvisation and doing different, unique things, but violent and toxic behavior will not be tolerated at this table.
The other, which I recently used, was to create a murder hobo NPC. In this case, I created an NPC called 'The Stabber' who was a demonic entity that would travel from body to body, possessing the person and using them as a stab happy criminal. However, one of the players got through to the stabber, and the stabber began to really like this player- they ended up dating, which meant that the party's job was to keep the stabber in line.
Instead of becoming the murder hobos, the party had to manage a murder hobo and try to teach him social skills. I put the party into situations where they absolutely had to deescalate situations, talk to the stabber about appropriate behavior, and work on healthy socialization to keep the party from getting into trouble. And by doing so, I both gave them an opportunity to practice advanced social skills, but also highlighted how awful murder hobos are and gave them an opportunity to be better than that.
And honestly, that's been a MUCH better alternative than sending a PC to jail. The party has been all in alignment on trying to manage the stabber, and it's been awesome to see them working together to try to teach the stabber how to be more humane.
And at this point, the stabber is now mostly a neutral character. One of his most recent quotes was, "Hey, I got backstage tickets to the theater- let's go see the play, then afterwards we can go stab the actors!" A definite improvement to what he'd be doing earlier, which would be trying to kill everyone there, and the player told him that he might want to avoid stabbing the actors, maybe they can stab some mannequins instead.
And the kid who said this had previously played a character that was very close to becoming a murder hobo.
Would love to hear your stories on how you deal with murder hobos at your table. Reach out to me at @rollforkindness on twitter. Also! I'm at PAX this upcoming weekend (8/30-9/2). If you see me, say hi! I'd love to hear about the cool stuff you're doing at your table.