Being a fat kid with OCD and Aspergers can be a bit tough, especially when every single thing has the potential to annoy you, if you want me to read your fan fiction AND enjoy it to its fullest extent, please follow these rules and regulations.

Rules I follow:
-reading/writing crossovers is strictly prohibited
-exceptions apply when:
~a supporting universe doesn't overpower the other   
~they are support characters that don't help the plot in a major way
~Do not use their POV
~Their original universes must fit each other's mood, examples of this done wrong would be as following: Steven Universe + Gravity falls/SVTFOE. 
Examples of it done kind of correctly: OTGW + Gravity falls (to some extent)
-if you do do a crossover, do not have two characters from different universes fall in love.