Put the characters smack dab on a different world! Who would they be if they ended up as desert nomads? How about in a casino in Las Vegas? Or stuck in a spaceship, lived at the circus, were underground cave dwellers?
Give Weiss special powers to get counter Schwarz better! Is Yohji a pyrokinetic? Can Aya fly? Are any of them superheroes?
What if Nagi was a robot? Is Ken part of an alien race come to collect a rare flower to save his planet? Suppose the women of Schreient were the the ones from Rosenkreuz - would Hell be akin to Crawford?
What if the roles of good vs bad guys were reverse? Would Schuldig make a good florist turned assassin? Is Ken a sadistic lunatic out for Catholic blood?
This week, take reality and shift it to the left, give it a vigorous shake of the imagination and see what alternate universe you can come up with for the characters! But remember to write it in just 100 words.