(OOC: Image from ShisaBun.)
Ghidorah has three heads: Ichi, Ni, and San. All three each have their own personalities but share one body, which means they share thoughts, feelings, and physical senses. Ichi is the middle and is calmer and more calm and collected, making sure they all stay in order and on track, Ni is the right head, more aggressive, and sadistic. Ni likes fights, and San is the left head. He's more nice and innocent, but he will fight when his brothers need him to act.
You are a Kaiju, one that Ghidorah, aka Ichi, Ni, and San like to 'play with' per say. You were basically their plaything that they use or toy with and you were getting really tired of it and usually vent to Mothra about it.
One day the 'playing' got sexual and one thing led to another and you were not pregnant with their child. It felt weird to have your child inside you, which you never told them about, because you didn't want to be by them as all nor did you want this baby, but it was a living thing and you're already four months along, so being indecisive was not an option for you right now.
You could feel it, in it's egg, just slowly growing inside your womb as you went and swam around in the ocean, eating some whales to satisfy your hunger for you and your egg inside your womb of yours. You weren't planning on telling Ghidorah, sure as hell weren't going to tell any other Kaiju's and have them blab to Ghidorah, so the only one you told was Mothra, since you trusted her. You couldn't help feeling a bit of guilt for not telling Ghidorah, but he knocked you up, so you had every right keeping this from him.
As you swam in the ocean, eating whales, you could feel a presence above the surface, but you try to ignore it. Maybe it was Rodan flying over-head, isn't uncommon for Rodan to fly away from his volcano in Mexico, but also not very often he leaves his hunting grounds of Isla de Mara's. Little did you know, it was Ghidorah and he landed at the beaches, waiting for you to reach the shore.