Taken from
laurus_nobilis and
rainmage.
1) Make a list of fifteen characters first, and keep it to yourself for the moment. (That way you're not leading the questions asked to fit the characters.)
2) Ask your f-list to post questions in the comments.
For example:
'One, Nine, Eleven and Fifteen are chosen by a prophecy to save the world from Four. Do they succeed?'
'Under what circumstances might Five and Seven fall in love?'
'Which character on the list would you most want on your side in a zombie invasion?'
'What would Two experience in Silent Hill?'
'What Pokémon would Eight have?'
'Write a drabble in which Two and Twelve FIGHT CRIME.'
3) After your f-list has asked enough questions, round them up and answer them using the fifteen characters you selected beforehand, then post them.
Go!