Erisian

Eresian (also known as merlunettian) is a non-binary xenogender in the celestial gender system. It is a combination of lunettian and mercurian. A eresian person may feel both at once or they may be fluid between them, or they may feel different amounts of each at different times.

Flag
The term ceresian and the flag were created by Tumblr user Juparian on December 31, 2017.

Etymology
The root of eresian is Eris, which is the name of a the second largest known dwarf planet.