Help pls

I'm trying to reread this manga where it's beastmen and humans and the dark colored human omega is from an orphanage with a creepy head beast men who's in charge of the orphanage (later tries to rape him while the omega digs up his mothers grave but gets saved by his fated pair) anyways so the human has a sister but ever since the human mated with a beast men his sister hates him cuz "she loved him more than a brother"(found out this info later in the story) anyways the human and the beast men are fated mates but they don't like each other so they made a contract with each other the omega sells his body basically and I know they have kids in another story. That's all I remember pls help