RPGMemes

Generally speaking, this is something that an experienced GM can handle in session zero. An important part of session zero is establishing expectations for the style of game to be played: Things like "are the player characters friends?" "Is PvP encouraged or discouraged?" "Do I as a DM want the characters to stick together?" etc etc.

Generally when running DnD, I request of my players to design characters who:

1. Have a disposition to get along well with their companions. (this can be for any reason: because they're like that with everyone, or because they're loyal to the group, or because they view it as useful to have some friendly scapegoats nearby or any other motivation.)
2. Be the kind of person who will go on adventures and take risks. (This can be because they're a daredevil, or because they're desperate, or because they're devoted to their duty, or any other motivation.)

Fundamentally, most DnD games are the story of a group of friends going on adventures together. If your DnD game is the story of a group of friends going on adventures, then it's extremely beneficial for your players to build characters who will be friends, and who will go on adventures. Together.

This shouldn't be the GMs job btw, players, roleplaying and backstory are YOUR department, write a reason why your character would end up with the others. Work together.

DM: As you walk away, you feel a slight tingle in the air before a flash as bright as a thousand suns blinds you for an instant before... nothing. A bolt of lightning has vaporized your body. Miraculously, nobody else in the vicinity seems to have been harmed in any way nor even do they seem to have noticed what just happened, including the fact that you just disappeared. It's as if the Gods themselves, for no particular reason, have arbitrarily decided to smite you out of existence entirely.

Ready to roll a new character?

If you don’t have a reason to work with the group, accept that this is a one-shot for you, which may be retcon’d as needed.

Fun fact:

The Expanse books (and eventual TV show) were started as a unique role-playing campaign where the person running it (Ty Franks) would write a prompt, the players would explain their character's reactions. He'd then write a story section incorporating that and the players would say how they reacted and so on.

There was a core group of characters who were the "survivors" early on, but one of the players had to drop out early-ish, so in the next bit of story that character died.

That was carried into the books and TV show, which is why after the core group of characters is established, there's a sudden, shocking death.

Everybody plays RPGs differently, but it's funny how some people don't get the term "roleplaying" and are constantly, relentlessly playing their real selves in the game. So you get barbarians with the sensibilities of software developers.

"Oh, you encounter a desert. There's nothing around for miles"

Basically my only rules for character creation are 1) your stuff must be from an officially published 5e rulebook, and 2) it must make sense for your characters to party up. It's really hard to make an interesting campaign for a group of four lone wolves who are totally disinterested in The Quest

THANK. YOU.

Players who do this ARE BAD PLAYERS. I don't care what it takes, you WILL find a reason to cooperate. Call it metagaming if you have to. This is a team game, you will work as a team.

Players are expected to make characters that will, for whatever reason, will work together and, for whatever reason, will take plot hooks. Without those two things the game doesn't happen.

The guy who splits the party on session 1: