I've mentioned before my interest in different demographic takes on the same concept, such as 7 Seeds (shoujo) and King of Thorns (shounen). Here's another: A young single man becomes the caretaker of a five-year-old girl.
Write it shounen and for laughs, and you might get Yotsuba&!. Write it shoujo and for teh oh noes melodramas (aging down the caretaker into high school), and you get something close to Aishiteruze Baby. Write it seinen and focus on relationship angst over the girl's dead mother, and there's Mizu Sahara's My Girl. Write it josei and focus on the daily difficulties of sudden single parenthood: Usagi Drop.
That's one for each of the four best-known demographics. Not only does the premise get used for completely different purposes, the main relationship skews all over the place, with the man being adoptive father, cousin, father, and nephew, respectively, of the girl. (Yes, nephew -- she's the illegitimate daughter of his just-dead grandfather.)
Interestingly adaptable premise, no? And these aren't the only versions I've met -- just the better ones. And I want more. Any suggestions? Especially stories as good as these?
(Not that anything's as good as Yotsuba&! ... )