And his partner Blakki
Sorry if it's a bit of a cheat to say two different characters, but I can't have one without the other. They're my oldest characters (probably like 15-20 years old at this point) and have gone through several dozen iterations but their designs have always been pretty close to their current forms. (the biggest change imo is Blakki’s skin tone, her original design was a super pasty white (like sunburn if exposed for like 20 minutes white))
Their dynamic has always been "most comfortable around each other" in the sense that they both get emboldened by the other. Once they get to the point in the story where they're comfortable around each other they start to get ridiculous and almost become the comic relief characters as well as being the protagonists.
Shouri doesn't want to put up with people's shit (especially antagonists) and loudly let's them know it, while Blakki keeps him calm. Though Blakki herself can be quite mean especially if her friends are hurt.
I wouldn't call them "heros" persay, they both reject the notion and don't really have a problem testing their moral compasses (such as stealing, destruction of public property, etc) . The main thing is they don't like seeing innocent people in front of them being hurt. Taking on the world's problems isn't what they set out to do. In fact, all of their motivations in any story they've been in have been mostly selfish but turn out to be for the greater good.
Example, in an older work I did for them, they ran away from home to escape Shouri's suffocating parents. They stayed on the run while being pursued by essentially hired thugs trying to capture them. In the intervening time they ended up foiling a plot that involved killing a large number of people by an unrelated third party simply because they happened to escape into the area where said third party was working on their machinations. In reality it could have been anyone to step up to play hero, but it was Shouri and Blakki simply because they happened to be in the area and were the best equipped to handle the situation at the time.
Wow I realize I've rambled on for a bit. I hope that's what you're looking for. I always have fun writing their relationships and interactions as you can probably tell by this