Need Of A Theme

If anyone feels like helping...i need to write a story for school...but i don't really have a theme... <_< dumb i know aih!
But i have characters...i'm going to use "The Twins" Hide and Seek Zwarte. And the genre is Fantasy Reality. :wacko: if that's a good idea...???
So if anyone has any good ideas...please share.
Thanks!!!!
:D

Do you think it will work? This is a Ext English 2 piece of work...which counts to my HSC...that's my final major life deciding exam.