Kingreaper
Adventurer
That would be the catch. In order for the player to make informed decisions, the player needs to know (or at least have some kind of idea) what the consequences of the PC's actions will be.
I think the best place to put that information is in the class itself.
Yes, but as a storyline aspect, it shouldn't be built into the mechanics.
Someone sending monster after you, granting boons to your enemies, etc. aren't the sort of things that have mechanics in D&D.
A paragraph mentioning that all the pact-based classes (primal, divine and warlock) may find themselves under threat if they choose to betray their patron, and that their patron may occasionally make requests, is all it really takes.
Note that with Warlocks, if done 4e style, I would expect betrayals to include such things as: Failing to kill cursed opponents regularly (the pactgranters seem to have a taste for souls or something
