So what do you get?
It is like mixing and matching where the biggest problem to cross pollinate science fiction / Fantasy universes is the mythos combinations and power leveling. who is stronger star trek or star wars?
I am doing fan fiction with star trek observing the star wars galaxy.. easy enough time ship to long long ago slipstream passage to that galaxy... but the mythos of Thor interwoven with the Professor and his X-men? The cosmic significance to the theme would be overwhelming but - possible IMO - given interjections by the transformers and combined with shields IronMan would temporally complete some of the circle.. but as with Good there is Bad... that might bleed.. hehe Bleed over to our reality in the acting out of our fantasies freely.
Who would say what to Whom? By and large there needs a partial story line plot arc across massive amounts of space/time.
How do the bad guys ... win.. or lose? and is this "fantasy" a result of just channel surfing again... I hope not.
IF anyone might have fan fiction idea themes it would be nice to see what you think?