I feel… like it probably depends on the crossover? XD
I haven’t -yet- made a real genre-hopping crossover before, like in the sense of “CRYSTAL GEM AINUR” or “MADMAX AU” or whatever, because, while I realize it’s super fun to try and find appropriate roles for certain characters in new environments, I kinda do enough of that already! Just in the regular Tolkien-verse, and its various extrapolations…
Modern Incarnation AUs are probably the closest I’ve gotten to a crossover (Melkor as an East German Punk Singer and Rad Queer activist coming to San Francisco in the 80′s while Sauron is an ex-military, big-business steel tycoon and stealth leather-community kingpin… that’s my favorite XD).
I’m not averse to crossovers? If you hit me with the right one that seemed like it had a lot of potential for exploring characters in a way that isn’t feasible in their original setting, I might be game? 🙂
UNLESS YOU JUST MEAN “CHARACTER FROM SERIES X COMES OVER AND PLAYS IN SERIES Y”, in which case, go for it! XD