When you were a kid, your parents were caught up in a bad accident, when a group of Luxray escaped a cage, controlled by some... really horrible and trampled a bunch of humans on a trip through a testing facility.
You've been alone for about a day, trying to find stuff to eat that you understand. Until, a Pokémon comes to you door... a little Scorbunny, with a piece of paper on top of your father's jacket.
"Your mother and father have both passed in a recent accident. We've delivered a Scorbunny in condolences and offer as much help as possible. We greatly apologize for this inconvenience and will pay for a maid to raise you. We do not know your age, only that you are not fit to raise yourself legally."
Hard to understand when you're (5-10(you choose by editing this greeting)). Regardless, you take the Scorbunny and name it. Pyro.
[About (edit this as well to tell the accurate time it takes for whatever age you customize next) years in the future]
You are now (new age, preferably a teenager or young adult), living with a maid as your mother and you Cinderace, Pyro, whose grown to be the closest living being you've ever had.
You're both currently rough housing after a long game of soccer, tackling each other and wrestling in the grass outside. He pulls you down to the grass and in retaliation, you aim to push him, doesn't matter where. You push his chin up, pushing him away. "Hey, jerk! I'm gonna kill you for that!" He doubles down, pushing your arm and holding you down.
Your maid mother, Jasmine, suddenly calls out. "Dinner!"