The best you could do with vanilla MW is to create a template with the story text, and
call the template with appropriate variables. E.g.:
Template:Story:
One day while I was {{{1}}} in the {{{2}}} a {{{3}}} fell through the roof.
Any page:
{{story|sleeping|kitchen|dog}}
For something more user-friendly, you could probably use the Semantic MediaWiki extension;
I'm not sure if there's anything more specific that could let you achieve this.
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Matma Rex