Fan Casting Et Tu, Brute? in Sort by Tropes

There's only one thing that can bring a seemingly invincible character to their knees: betrayal. Having the entire Evil Empire out to get them isn't a big deal as long as they have their True Companions watching their backs. But if one of the chosen few should renege, the hero will go to pieces. It doesn't have to be anything as dramatic as switching sides or selling out to the Big Bad. If one makes a few scathing comments about their leadership skills, or another holds the hero responsible for his Cynicism Catalyst, the results can be as devastating as though they'd painted a target on their pal's head and handed out sniper rifles.