Ballon d'Or rivalry has nothing to do with the Champions League. So when Man City has to play against Real Madrid it is not an individual battle between Vini and Rodri because it will always involve many people, and their existence and contributions are much more important than Vini or Rodri.
Talking about opportunities, Real Madrid seems to have a better chance than Man City, because they are not as bad as Man City. It's just that there is one thing they don't do when they have a chance, which is not to bring in new players (especially defenders), though Ancelotti should know very well that their defense line really sucks.
Bringing personal problems to the field is an action that will damage teamwork, so I don't think Vinicius has a revenge mission as discussed. Because the news was exaggerated by his fans, Rodri is still injured so there is no reason to prove themselves to each other. Let the past pass, now Vinicius only needs to focus on winning against Man City and being able to play solidly.
Giving Vinicius his best performance would be the best thing for him to show to all the fans. There is no need for any way to repay such a thing except with the best performance that can be shown. I hope Vinicius will appear in the best condition and score goals.
The award issue is over, indeed some fans think it is unfair. But Vinicius must focus on playing and giving his best to bring Madrid to victory. He is a great player and he must show his ability.