Omegas Stand (HXH)

Shalnark is the omega of his pack, not really searching for his fated mate, when he goes into heat during one of the troupes missions he realizes Uvogin is his fated mate since he tried to mark him.
Shizuku and Feitan are late bloomers but everyone assumes Feitan is a beta and Shizuku is a Delta, when proven they are Omegas as well when they go into heat during Shalnark's it is shown Phinks is Feitan's Fated mate and Machi is Shizuku's and Shalnark is in charge of Protecting them from getting taken by them.
When Chrollo finds his fated mate he forces her To come back to the troupes base and when Shalnark realizes this he protects her as well from an angry and horny Chrollo.
Kurapika and Gon go into heat while being kidnapped by the troupe resulting Leorio and Killua to react by showing they are their Fated mates, again Shalnark drags them into the omega den of the hideout not caring they are enemies.
Illumi is kicked out after being found out by his parents he's an omega, Hisoka finds him and reacts to his scent proving he's his fated mate, Shalnark finds this out and has Illumi join them.
And a duo of an Alpha and an In heat omega come by and the Alpha feels it's his job to teach the Alphas how to treat their fated mates.
It's basically just Shalnark and the marked omega being mothers to the omegas and the tops getting taught a lesson in manners and love.