Another question-thingee

So, I wrote a fanfic thing (as it happens, it was a thing that was supposed to be a ficlet, but ended up being 1,500 words long). Dunno what to call it, genre-wise, since it's apparently the bastard lovechild of an AU fic and a crossover. (Basically, it's a 'Characters from Series A if they had been born into the world of Series B, and now they are meeting a canon character form Series B') Granted, it makes a bit more sense than 'Oh, a portal opens up and there's a crossover!'. On the other hand, since it does change some details of the characters, I wouldn't want to call it a crossover on its own. Is AU-crossover-thing an appropriate genre?

And this all started because I wanted to write a conversation between two characters.