Disclaimer: I have never actually played Dresden Files, or even a Fate game. I have read through parts of the book, a wiki article, and listened to an "actual play" podcast. In other words, I might have interpreted aspects grossly incorrectly.
Building a D&D character goes beyond choosing a race, class, feats, skills, and gear. Regardless of what detractors might think there are about six and a half pages--starting on page 18--devoted to role-playing, with a few pages telling you to go through the motions of choosing some personality traits, mannerisms, describing your character, and if possible answering a few questions about your background and motivations. In past editions DMs I played with would award--or penalize--you with "role-playing" experience depending on how well you played your character and adhered to your alignment. Nowadays this practice has fallen out of use in my gaming circle, which is fine because some players do not want to engage in extensive social role-play (or are just really bad at it and/or derive fun from other sources).
While I encourage my players to think up flavor material for their character--especially anything I can use as an adventure hook--I most often find them missing from characters, particularly those of the casual members. On the other hand some players take a few sessions to figure out their character's identity, while others are just happy to give me a rough motivation and leave it at that. I had entertained the idea of starting to award players with bonus XP, but depending on the level it might not make any difference at all, and even then probably for only a session. It was much more effective in older editions when classes advanced at different rates and had various means of gaining it; thieves from getting cold, wizards from casting spells, etc. It was even kind of useful in 3rd Edition, because as a wizard I could set it aside as my item creation fund.
With that in mind one possibility I had considered would be to give the entire group bonus XP for socially role-playing their characters well, but then you could have a few talented players pulling the weight of everyone else, in a similar vein to the theoretical party with a player's theoretical farmboy-who-picked-up-a-sword-to-fight-orcs.
A better idea is one that I found in another game entirely: Dresden Files RPG. This game uses the Fate system, which puts a much, much larger emphasis on a character's personality, background, and motivations to the effect that you are supposed to sit down and basically have a "collaboration session" with the other players.
In D&D your personality does not have any mechanical bearing on what your character does, instead providing a benchmark for stuff your character is likely--or unlikely--to do. If a character acts within these parameters, then great. If not, then it falls to the DM to correct the course of action (or get into a debate until everyone comes to an acceptable conclusion).
In Fate you have character elements called aspects. These constitute a diverse array of character elements--personality, physical traits, motivations, even items--that make up the character as a whole. Examples could be silver-tongued, greedy, reckless, or an item like a family sword. Aspects are not limited to the characters; non-player characters, objects, or even areas can have aspects; for example a cutpurse could be desperate, while a cliff could be slippery from rain, or a crate could be highly flammable.
Aspects have a double-edged purpose. First, you can "tag" them in a situation or challenge in order to gain a bonus. A greedy dwarf, for example, might be driven to succeed where there is money involved. On the other hand, the Gamemaster can also "compel" an aspect, essentially forcing you to do something. The same greedy dwarf might be compelled to betray one or more friends in exchange for a sizable bribe. Now, players can refuse a compel by giving up a Fate point, but if they go along then they gain a Fate point. In this way Fate points could be seen as a kind of story-directing currency.
With all this in mind I wanted to create a mechanic by which a player could receive an immediate benefit by doing stuff that their character should be doing anyway. An incentive to get into the social aspect of the game, as it were. I thought about a rule where characters could tag their aspects for a small benefit, or require them to spend action points to get the benefit, potentially making it a variable bonus like how action points worked in 3rd Edition, or just giving a re-roll. The more I thought about it, the more it started to sound like the potential changes to skills that Mearls was talking about last week (which I would be interested to see an Unearthed Arcana article for).
Anyway, if you want to use aspects and fate points in your games, then I would first have each player create a list of at least three aspects, but probably no more than five. Aspects that can be both beneficial and detrimental are best. There is a pretty sizable list here. These can be derived from your character's personality traits, racial tropes, mannerisms, motivations, goals, connections, etc, or be generated in place of all those things.
For fate points, I would work them as follows:
- Action points pull double-duty as fate points. They still give normally give you an extra action.
- A player can tag one of her own aspects and spend an action point to gain either a 1d6 bonus to the check, attack, or defense. Alternatively you could re-roll the check entirely/force a re-roll (for example, if you are attacked or a creature is making an opposed check).
- A player can spend an action point to gain a measure of control over the direction of the story based on the aspect of a creature, object, or environment. The DM can grant the invoking player an action point to waive the compel.
- The DM can compel a character to do something based on one of her aspects, or cause something to happen based on the aspect of a creature, object, or environment. If the player allows this to happen, she gains an action point. She can instead pay an action point to waive the compel.