I, Shiro Chin, was asked to share my lifelong knowledge on how to avoid getting decapitated, robbed and tossed in a lake filled with bloated dead bodies despite regularly meeting with groups of bloodthirsty adventurers. Worry not, I have a crash course for you folks to make sure you understand what to do next time you fear for your life when faced with such individuals devoid of all compassion.
The first step in understanding adventurers’ behaviour is understanding what fuels their bravery: Greed. They exist for the sole purpose of stripping dead bodies of their valuables and hoarding them in chests they then hide around their tent-filled slums. They call this the art of “Looting”, and some of them are proficient at it: In mere seconds you are already wiped free of any coins wedged in the linings of your pockets.
Now that you understand the motive behind their career, which is really just armed robbery, you can move on to keeping their attention from you. For this, you will need to start giving them “Quests”. Those can be anything, really, such as telling them to go collect mushrooms in a Yeti's cave, or showing them the path to the woods where weird faes were seen. The idea, however, is that it needs to sound dangerous enough for them to believe in whatever task you are handing them, else they might think you are trying to fool them! And don’t ever think about asking them to find your long-lost family heirloom, for should they find it you might as well discover it later among a merchant’s wares.
However, fair warning, despite all your efforts at sending them to the most perilous places you could imagine, they will keep coming back. Those who die create more treasures for the survivors, and for each one who meets his final death, new ones, stronger ones, keep replacing them. Truly a nightmare, isn’t it?
Best of luck, and never forget avoiding adventurers altogether is always better than having to make-up weird questing stories on the spot.