The way I build a character's personality and story is to start with the 'hook'.

What makes this character different (not their build or powers)?

Do they have a particular ambition? Conquer the world? Save their home village of throckmorton from the ravaging orc hordes? Impress Prince Pretty Hair so he'll marry you? Write a song so beautiful that Gods weep to hear you play it?

Is your backstory different? Raised by a vampire who longed for the days of living and was alternatively cruel and kind as whim took her? Half-elven in search of a father who left when you were an infant? Trained as a emotionless warrior since childhood who has now run away after beginning to fall in love?

Do you have an enemy that's odd or unusual? The local lord has been harrassing your family and particularly you and you don't know why?

Do you have a particular habit or vice? You can't resist beautiful married women? Do you have wanderlust and just can't sit still? Can't stay away from booze? Always have to be whistling a tune?

And so forth. I find that once you have a hook, you just work through the rest. Ask yourself questions about what you look like? What is your social class? How many children were there in the family? What is your current relationship to your family? Where are they? What do you like to do with your spare time? etc.