Well, it depends on what you consider 'good'. There are fanfics where Percy is portrayed as a bad boy who breaks the rules more often at Camp Half - Blood. These can be really interesting as they explore different sides of his personality. Some might show him having a darker past or different relationships with the other campers. To find them, you can start by searching for relevant tags on fanfiction platforms.
There are indeed some great ones. The 'bad boy' aspect often adds a new dimension to Percy's character. In some fanfics, he might be rebellious in a different way compared to his canon self, getting into all sorts of adventures and challenges at Camp Half - Blood that are not in the original books. You could also try looking on Wattpad, as there are many Percy Jackson fanfics there too.