I currently run a homebrew campaign with 6 PCs, one of which is a paladin. The main goal of the campaign is to travel to the center of an area of magical corruption and try to put a stop to it. Nobody knows what causes the corruption, and it is spreading quickly.
In their endless quest to completely ignore the main plotline, they managed to go on a plane-hopping adventure.
So, here's the problem. During this plane hopping escapade I thought it would be fun to have the party approached by a deal-making demon. He asked if anyone interested in making a deal please enter his tent. The demon's intent was to slowly steer the party towards the center of the corruption, because he too had a vested interest in it being stopped (More on that later). Now, I was hoping that one of the neutral characters would be interested, and if all else fails the LE Gunslinger might be game... but I was wrong.
The paladin stepped up.
The paladin entered the demon's tent, arms crossed and head full of "I'm so g*%!~#n good there's no way this demon can pull one over on me"-ness and asked what the demon wanted. The demon simply said he wanted to show the paladin something, and that all he required was that the paladin place his hands on the same table the demon was. The paladin obliged. The demon showed him a battle that would take place in the future and how to stop it. But that wasn't all he did.
Now the paladin sees "Holy" golden light on areas and people of interest, actually caused by the demon, whom the paladin allowed into his mind.
So the question is this, should the paladin fall for making a deal with a demon? One of the main reasons I'm leaning towards yes is that one of his god's things is: "never associates or parleys with evil gods or fiends."
I know that this particular scenario doesn't exactly follow the rules listed here because I didn't warn him that "Hey by the way making deals with the devil is like, not a good thing to do, or smart either." But at what point am I holding his hand?
So, should the paladin fall?