We should be writing crossovers!
I thought crossovers only appeal to fans of both works, and hence that works the opposite of the way you thought it would?
Huh. Now that you mention it, maybe they do. I've certainly read crossovers of series I don't read, but...
"The kind of classic fifties-era first-contact story that Jonathan Swift might have written, if Jonathan Swift had had a background in game theory."
-- (Hugo nominee) Peter Watts, "In Praise of Baby-Eating"
Three Worlds Collide is a story I wrote to illustrate some points on naturalistic metaethics and diverse other issues of rational conduct. It grew, as such things do, into a small novella. On publication, it proved widely popular and widely criticized. Be warned that the story, as it wrote itself, ended up containing some profanity and PG-13 content.
PDF version here.