In tomorrow's article, I'll give a bunch of hints and tips on how to actually generate these ideas so you can use the same tricks as I have in order to help flesh out your own characters. For now, I'm just going to show you one I'll prepare in about fifteen minutes which I'll be playing in the Pathfinder Adventure Path: Carrion Crown.
So, the original concept was a highly feminine female sorcerer. I've done a gritty Paladin / Gunslinger and I've done a bratty young Psion and a rather pragmatic Cleric, but I've never done someone who could be called feminine.
So what makes someone highly feminine? Brainstorm time: vain, impractical clothing, anxious when personal hygiene standards drop, nice hair, make-up kit, few physical skills, turns to men to do the heavy lifting, doesn't swear, is flirtatious with handsome men, flirtatious with handsome men, and (in that era) requires privacy to maintain decorum, swoons a bit from horror and seeks out masculine protection.
I decided to make it more complex by making her a fae-blooded Changeling sorcerer which will influence her to be easily distracted, superficial, highly emotional, find beauty in the strangest of places, a bit vague, innocent of the actual dangers, and a staunch romantic.
Her internal motivation will be a drive toward Self-Empowerment. It's a rather vague drive, so it fits, as it's deeply personal and, unlike a drive toward Power, doesn't have easily measured benchmarks. After all, one person's Self-Empowerment is another person's personal hell. So she'll be curious and enjoy exploring things. She sees it as a journey of Self-Discovery (but that's just a blind) but in truth she spends too much time 'feeling' than 'doing' as it is and thus it's more about overcoming her personal barriers and becoming a more 'whole' person.
She may rant and rave about being forced to abandon all of her pretty possessions for a slog through the swamp but will be quite happy once she's done it and realised it wasn't so bad. Especially since she saw the most beautiful swampy sun-set and those black twigs were kind of artistic, anyway. And, ooh, next time she'll be the one keen to try the road less travelled just so she can see something different.
So, by the 90% / 10% rule of strange, 90% of the time she'll seem the predictable princess but every so often she'll show compassion or change to accept something new. Which should hopefully keep her from being too irritating.
She even has a secret that will whomp her in the face when she learns about it. Her history is that she came from a failed aristocratic family who sent her off on this 'journey' with what was left of their earnings because they knew they were going into the poor house and they killed themselves rather than face poverty. Too many gambling debts. This may come up during the game, or at the end, or not at all if she dies or the Dungeon Master chooses but it certainly flavors things and suggests the style of her upbringing.
Anyway, hope you found this somewhat interesting! Happy gaming!