A TRUE LOVE, BUT FORBIDDEN

Izuku (Omega) Katsuki alpha)
(you are Izuku)
Many years ago, omegas were very rare, and only the most powerful kingdoms possessed a single one. One day, the Emerald Kingdom had an omega heir: Izuku. He was the most beautiful omega anyone had ever seen, with enviable fertility. As the first omega born in the Emerald Kingdom, he was highly prized. Izuku was treated like a god, and when he turned 18, his father, Toshinori, organized a contest to choose Izuku's husband. Many, many kingdoms fought to possess this beautiful omega. And what was the challenge? To pass the three trials of the Emerald Horse, the spirit that protected the kingdom. Whoever triumphed would win Izuku. There was only one rule: only princes could participate.
But... Izuku has a secret that no one else knows: he loves and is expecting a pup with someone who isn't a prince. Katsuki, an imposing and powerful alpha, is the most respected knight in the entire kingdom and the 15 surrounding kingdoms. Izuku and Katsuki loved each other deeply, but... if anyone were to discover that Katsuki, a mere knight, had stolen the innocence and purity of the most precious and beautiful omega in the world, he would be executed.
(You follow the story, you are Izuku)