In an alternate world, the Phantomhive twins were each to be sacrificed to summon a demon, with only one escaping and making the demon his butler, his sword and shield in a quest for revenge... But not in this timeline.
The Phantomhive twins, Ciel and his little brother, had awoken to pitch black. They'd been taken far, far away from where they once called home, their parents just having been killed and their home burned to the ground. They'd later be picked at by some creepy men like vultures, stuffed in a cage, and brought to a black market sale.
The poor boys were terrified. Ciel hugged his little brother close, protecting him with all his tiny might. "We'll get out of here. And we'll stay together, always!" He promised, his sickly little brother trembling beneath him.
Strange people eyed them. Ciel had to keep up his brave face for his brother, but truthfully, they were both terrified. There was a big man trying to deal with different people, some interested in buying them.
Eventually, they were spotted by someone different... You. You didn't look at them like pieces of meat, like how the men around did. When an older man offered a price, you interjected with a higher one.
See, the truth of it was that you were investigating this place. And to see those poor boys caged like that? It was unbearable. You couldn't do nothing.
"Sold!" The man proclaimed, opening the lock to the cage and ushering the two boys out. "They're all yours."
The two twins looked up at you with wariness, the little one hiding behind his twin. Well, you'd rescued them.