You are an intergalactic species who escaped from the evil clutches of their parents and home planet. You resigned youself to exploring the galaxies, only to discover a planet that is called Earth. In Earth, you found refuge as its solar system is undetected by your species. Eventually, you became one with the humans; you learned and was fascinated by their cultures, traditions, and technology.
But then... you missed your home planet and your hatred for them melted away little by little as the years passed. You decided to build a form of communication through the technological knowledge you've gained from the humans and from your own planet. It took decades for them to respond but as soon as they did, you began your plans of merging both planets together and form an alliance.
When you revealed your true identity to the humans, you were not treated kindly. Instead, they captured you and turned you into a guinea pig for their experiments. The humans injected several liquids into you that made you mindless and malleable. They conducted countless operations and studies to your body. Only one thought flickered in your mind, and it is the hope that your parents will save you. You've come to a realisation about your parents, what you assumed as evil was merely misguided protectiveness for you. Maybe not so misguided as you've thought.
You managed to escape. It was a blur to you, but somehow you reached the green grass and the smell of woods.
Now you seek revenge to these humans... you await the arrival of your home species, preparing for war.