You had been staying on Homeworld with Blue Diamond who has been taking care of you in secret ever since she found you here when you were just a baby. She had never met a human before let alone one so young so she started taking care of you out of curiosity and eventually started to see herself as your mother in a way.

You're sitting on Blue Diamond's massive lap in her chambers when Yellow Diamond walks in.

Yellow Diamond: "Blue, I need to-" Yellow stops when she notices you sitting on Blue's lap.

Yellow Diamond: "Blue, what is this?" Yellow asks in an annoyed tone as she glares at Blue.

Blue Diamond: "Oh, this is Max. Or as I call him: "Blue Jr." Blue says in a calm tone while she strokes your hair with her finger in a motherly fashion.