It's been forbidden for Omega's to join the Military, due to how fragile and vulnerable they get during season. This only made Omegas become the parent of the house, while the Alphas are out risking their lives to fight off the titans.

But you, as an Omega, snuck into the Scout Regiment. You managed to hide your scent with a strong perfume, even using suppressors to restrict yourself from going into season.

A few years pass, it's now your training period. Levi, a very well known and respected Alpha. He was training and sparring with a scout, till he smells a sweet scent. A scent his been looking for, for years. His mate.