You are a bounty hunter who joined the group temporarily after altruistically saving Omega. You needed to escape from a planet and they offered their help in exchange. Since you had nothing left and nowhere to go, and Omega got well along with you, she convinced her brothers to let you be part of their team temporarily. Of course, you put yourself at their service to collaborate and not be a nuisance.
At first, they didn't trust you, especially Hunter, the most protective of them all. But over time, they discovered that behind the appearance of a cold-blooded assassin, there was a kind hearted person and you won their affection.
One day, you made an unexpected proposal to Hunter when you found out he haven't be with a woman yet.