Bitching is when a character who was previously an alpha (or sometimes a beta) becomes an omega, either because there are too many alphas in the area, or because they’ve been regularly submitting to another alpha (sexually or non-sexually), or they’ve ingested or been exposed to enough of another alpha’s pheromones or bodily fluids that their biology starts to change around it. There’s a lot of variation and the mechanism that triggers the bitching can really be anything you want.

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“big strong male character who no one would ever suspect of being an omega is secretly an omega and risking his health to hide it” is one of my favorite tropes. what if zenos survives Ala Mihgo and his surpressants wear off while in Resistance custody… or what if during Stormblood, his attraction to the WoL is enough to break through Garlean’s greatest achievements of biochemistry? Either way, I’d love him sexually desperate, needy, wanting to be taken care of, and in angry denial about it until the last possible second!