One of my players is creating a PC with a strict honesty personality. Since this is a defining characteristic for the PC, she wants a trait based on this. Any thoughts on one that will work? Or, if a custom trait needs to be created, what would be appropriate?
Hey, Dustin. You might want to borrow from the traits outlined in the 3.5 product Unearthed Arcana as a foundation. Here's a link to the Hypertext D20 SRD where they outline a different kind of trait system and give you an honesty trait that could help guide you. Notice that Unearthed Arcana's trait system always builds in a hindrance in exchange for the benefit. Pathfinder's trait system doesn't hinge on that kind of balance. Instead, each trait is equal to about "half a feat" in terms of power. And, most campaigns get started by letting the PCs have their pick of two traits (which equates to a free feat) to help round out their character concept.
If your player is going to go with the notion that her honesty trait serves as both a boon and a hindrance in certain situations, you could probably still go with Unearthed Arcana's version, but you'd need to pump up the benefit side of it by another +1 (and maybe even grant Diplomacy as a class skill if her class doesn't already have it).
Thus, you could word it like this:
You are a naturally straightforward and sincere person. This quality helps persuade people to your viewpoint, but you have difficulty telling lies and prove more gullible since you expect the same of others. You gain a +2 bonus on Diplomacy checks and Diplomacy is always a class skill for you. However, you also take a -1 penalty on Bluff and Sense Motive checks.
My two cents,
--Neil
+1 to diplomacy, and diplomacy is always a class skill for you.
Its a fairly standard trait format, done with any skill.
Alternately, if you want more powerful:
+1 to diplomacy and sense motive, and one of these (your choice) is always a class skill for you
+1 to diplomacy and sense motive, and one of these (your choice) is always a class skill for you
This.
30 Character Motivations (PFRPG) PDF
You could look into this, one of the motivations is Honesty, and is probably just what you're looking for.