I need help with character development

I'm thinking something to do with the team, like perhaps it has something the rival wants or needs, and during an encounter between the main character, rival and the team, the main character's actions (which follow the supposed "right thing" line of thinking) are at odds with the rival getting what he needs, maybe through a bribe or extortion plot between the team and you two (team knows it has something rival wants, will give it if they cooperate with aspect of their overall plan, main character will not cooperate looking out for the greater good). Rival misses his chance of ever getting what he wants/needs, creating not only a personal vendetta between the rival and the main character but also a descent into a general callous mindset like Silver had all along in Gen 2. The exact details would be on you to work out of course but this kind of scenario would be what I would probably do for a turn, happening somewhere in the middle or the story or near to it.

It could be a gradual thing too if you wanted it to be, such as at first he's angry but is able to accept it's for the greater good, but the loss chips away at him over a period of time.