>>15502967Well, since this is the Pokemon Anime we're talking about, it might be a little obvious, but here goes.
He watched his brother, who had attained every badge in most regions, lose mercilessly. Reggie trained with compassion and leniency, so, in order to avoid the same outcome Reggie had against Brandon i.e. a 'failed' trainer, Paul goes the opposite road. Paul meets Ash, who raises Pokemon just like his brother did... that is the main reason Paul ridicules Ash instantly, because if he accepts Ash, then he must also accept his Reggie and his training methods, the same methods Paul attributes to his devastating defeat -- which makes no sense to him, which is why he's so 'stubborn'. To Paul, that is the only variable he can see as to why his brother lost and the only reason his methods are so different, which shows he had huge respect for him prior to that incident. Of course, the fact that Reggie gave up being a Pokemon trainer right after that further aids in Paul's process of trying to make sense of it all.
The real plot point happen in their battles. If Paul wins against Ash, then his views are justified and he will never be able to accept neither him nor his brother as decent trainers. He was deluded from the start, all due to that match between Reggie and Brandon.
The final match allowed Paul to finally accept his brother. As well as acknowledge his misguided way of thinking i.e. a trainer's ability is composed of how they raise their pokemon, instead of actual skill. To Paul, he believes he's strong because he raises Pokemon differently, instead of the fact that he ~is~ a skilled trainer. The whole rivalry was about him coming to terms with himself and his family. Like i said before though, he became that way because that is the only variable Paul could grasp as to why someone with so much experience, Reggie, could lose so horribly and so quickly.
tl;dr Reggie's a bitch and it's all his fault
