Percival's parents lived on a sheltered, mountainside area in the northern regions of Kanto, where there was minimal contact, if any, with much of the outside world. As such, he didn't really get to experience much in the way of social activity, and instead turned his attention to Pokemon. And, since they lived in a very remote location, there were lots of them. However, for a long time, he was never allowed to roam around the area, due to the other, more dangerous species that also visited on occasion. When Percival's 13th birthday rolled around, he was given the family pet of sorts, a Beldum named Mercury, as well as receiving permission to travel through the mountains in search of discoveries. And he gladly did so.
But the first creature he encountered was definitely not able to be handled. Percival had strayed a good few miles from his home, only to stumble through the hunting grounds of a fierce Charizard who patrolled the place. Not taking lightly to intruders, it began spewing blistering flames. Percival had seen the attack coming just soon enough to avoid getting roasted alive, but his right arm took a good majority of the heat, while Mercury had been hit directly, falling to the ground like a sack of potatoes. The behemoth then swooped down to finish off the terrified Percival, but before it got the chance to do so, a blinding flash permeated the area, sending the Charizard flying. The attack was a SolarBeam, used by a Solrock who was not too far away.
Also visible was a Lunatone, who was currently hurtling boulders at the reptilian menace, the majority of them hitting their mark. They appeared to be under the command of two young twins, with nearly identical appearances. Percival had the common sense to get out of the way, and not soon afterwards, the Charizard began flying away. It ends up that the two twins were none other than Tate and Liza , Gym Leaders from the Hoenn region. They were just about to contact Percival about an apprenticeship at their Gym in _________, (Gym location, will fill in once region has been decided), and coincidentally stumbled upon the Charizard. Percival was grateful, for both offering him the position, and saving his life. After a quick visit and confirmation from his parents, he was allowed to go.