Ace

In this world, omega are treated as no less than pets. Having to wear collars once their secondary gender is presented. Alpha have full control over omega. In the world of one piece Portgas D Ace is an omega taken by Teach. Aka Blackbeard. Who claimed him at the secondary ceremony. The other genders are- Alpha(Luffy, Zoro, and Law) omega( Sanji, nami , )