Many writers create a timeline recording the activities and important information about the characters in their books. Major character milestones are recorded to help the writer remember important plot points.
Over the last week I made a spreadsheet and gave my ONE LIFE characters (even the minor characters) a unique birthday, death date, wedding date, day they bought their house, etc. I know the exact month/day/year sixteen years ago when one character immigrated to another country. Also, I have an exact month/day/year from twenty years ago when two characters were set up on a blind date. Each character's physical characteristics and country of citizenship are recorded. Is it strange I find this kind of work fun?
Other News: Vampire Diaries was A+ on Thursday (they did such a great job casting that show)! Check out the books by L. J. Smith, if you have a chance.