The Unwilling Omega
If Tsukishima had to pick one thing he hated the most, more than anything in the world, it was presenting as an omega. Not that there was anything wrong with being an omega, but for Tsukishima, it was the worst. His parents were both betas, and even though his older brother had presented as an omega, and siblings tended to share class traits, everyone thought the younger brother would present as an alpha, or at the very least a beta like his parents.
He had most of the traits that had been stereotyped as alpha, and none of the traits of an omega. When he hadn’t had a heat by the time he was fourteen, he figured he was an alpha. When he hadn’t had a rut by the time he was fifteen, he assumed he was beta. He was completely fine with that. He wouldn’t be bothered by heats like his older brother Akiteru and he wouldn’t lose his mind around omegas like the alphas he knew.
Yes, being a beta was just fine.
And then he started high school at Karasuno.