lixvseverything asked: Your "XX-Myn" concept is rather cissexist, no? XX does not equal female. Female does not equal XX.
I considered that and sallied forth anyway for three reasons. 1) Trans* characters are explicitly welcome on the LGBTfenders, 2) One could use their fic/art as an opportunity to satirize cissexism, and 3) because I could not think of any trans* mutant characters of all the mutants that have ever been in the history of the X-Men, unless you count Mystique.