So here's an idea for an NPC that players can meet in a city environment (often a tavern)... The Dungeon Broker.
This character will only fit in a campaign where there are plenty of dungeons to explore from many past civilizations and old powers. In other words, a world where dungeon running is as much a trope for the inhabitants of the world as it is for the players themselves.
The Dungeon Broker could be a businessman without scruples, a crime boss, or perhaps even in some settings, a Dungeon Broker can do just that full-time; dungeon brokering. (Up to you to decide if there's only one Broker in a city or even a setting or if there are many to the point where it is a profession as common as city guard captain or crime boss.)
Now, what is a Dungeon Broker exactly? Simple. In a world filled with clues, old maps and legends to ancient dungeons and other places reportedly full of treasure for those brave enough to go there, the Dungeon Broker is the guy who hands out said maps and clues... for a cut of the final treasure.
Reasons for the Dungeon Broker to not go after the treasures himself can be many. Some possibilities could be (but are certainly not limited to):
- It's more profitable for him to distribute many maps and clues and then collect his share from returning adventurers than it would be to spend his time going into one dungeon after the other.
- He is too busy with his main business to go exploring. Maybe a crime boss doesn't trust his men not to take over if he leaves the city for too long, or maybe he needs all his men for a war against another gang.
- He simply has a distaste for the danger it involves.
There are many ways a Dungeon Broker can ensure that the adventurers will give him his share of the treasure once they're back. While some might work with legal contracts, trust and a handshake, or good old coercing, most Dungeon Brokers who aren't spellcasters themselves will want to hire one. The Geas spell is often the most used, and normally adventurers who deal with Dungeon Brokers regularly will come to expect and agree to being put under the spell. If not, that's fine, but the Dungeon Broker will keep his maps and clues for himself. That also means that a Dungeon Broker needs to spend a significant amount of coin in protection to avoid having a group of adventurers just rob him. (Which is no guarantee for stopping such events from happening of course.) When all is said and done, a smart Dungeon Broker NEVER keeps maps and such on himself, and even less in his known place of business where everyone will expect those to be. But not all of them will necessarily be smart.
Broker shares will depend on each Dungeon Broker and each specific setting.
Dungeon Brokers also afford an easy way to offer different possibilities to players while also scaling each place according to the group's average level, if such things matter to you. At first, a Dungeon Broker would not trust his best map to a group he just met, so he'd send them to some unimportant dungeon with perhaps a few worthy items to be possibly brought back. As the adventurers continue doing business with the Broker, he'll trust them with more and more promising locations.
A good way for a DM to use the Broker would be to have many dungeons/adventures ready. The Broker then tells the adventurers what jobs he has available (while leaving enough details vague so the adventurers cannot guess where that would be before making an official deal with the Broker.) Once the players pick one of the adventure hooks, you'll know which dungeon/module to run for them.