So first, a little backstory. I'm genderfluid, and for most of the time i've known i'm genderfluid, i've thought of my fluidity as gliding around on a 2-axis scale, as seen below:
One axis going from male to female, and another going from "yes gender" to "no gender". Simple as. This model served me well, and it mapped quite well onto my experiences; specifically, what pronouns i prefer at any one time, which is the usual test i do to determine how i'm feeling. But then i thought:
Wait... does it? I mean... yeah, it works pretty well for "he", "she", and "they", but when i'm going by my neopronouns, it just completely breaks down— what the hell does it mean for my gender if i want to be called "vem"?
Out of this frustration was born...
The Gender Tetrahedron
Instead of two axes, the Tetrahedron has four points: male, female, agender, and an identity wholly apart from the other three which i have, for lack of a better term, decided to call vetrois.
The term comes from ve and the French trois ("three"); it's pronounced /vɛ.ˈtwɑː/ (veh-twah) or /viːˈtwɑː/ (vee-twah).
I chose vetrois over other terms because non-binary and genderqueer were too non-specific, and i use them to describe myself whatever my feeling of the day. I didn't feel comfortable coöpting specific cultural words for third genders; neither androgyne or neutrois really fit, and i didn't really want to use anything ending with -gender. So... a new coinage it was!
Near the male point i prefer he/him; near the female point i prefer she/her, and near the vetrois point i prefer ve/vem/vir. I'm fine with they/them basically whenever i'm not hugging one of the walls.
The Tetrahedron still has a fair few oddities, because any mapping of the complex realm that is human gender down to a set of sliders and axes will necessarily leave something out— but for the time being, that's fine by me.