What make them mad?
What makes them cry?
What do they do well?
What do they look forward to?
Who broke their heart?
What did they want to be when they grew up?
What happened instead?
If they had only one day left to live, how would they spend it?
If you find there’s not enough conflict in your story, check whether the opposing characters have different enough answers.
And if you're brave you may want to ask yourself these questions, too!
(For friendly, supportive advice on writing your project from idea through to publication or produciton, see Your Writing Coach, published by Nicholas Brealey and available from Amazon or your other favorite book seller.)