You can't deal with this objectively. Regardless what you do or don't know about him, your 'stake' is exactly part of the reason why you shouldn't have any part of this.

I know he wronged you. But he is dangerous, Rin -- and getting involved in what happens next only paints a bigger target over you moving forward. In a place like this where the game can change at the drop of a hat, you can't make reckless decisions based on a sense of personal vendetta.

...Believe me, I know that isn't always easy.