Imagine a group of powerful people.
Imagine these are particularly paranoid powerful people; and among other things they really fear losing their power. Likewise they fear the breaking and invalidation of their own peculiar power structure.
Imagine these people are, along with being particularly paranoid, also disgracefully ruthless, remarkably stubborn, and surprisingly crafty.
Imagine that they enforce a strict and viscious line, not just from the marks, but from within their own ranks.
Imagine that an oath/pledge is what guides their line. Set in stone.
Imagine that these people's opposition has for long been all but helpless before them, even as the marks themselves are.
Imagine that the marks and the opposition decide to challenge, to fight back. The challenge is rather concilliatory, relatively speaking. It's somewhere between full surrender and meeting halfway. But powerful people have portly pride, and these are no exception. And it doesn't do to be caught breaking one's oaths/pledges. Word will get around.
So what do these people do? They react; swiftly and visciously. Any and all challenges are to be dealt with, and laughed at. Wounded and casualties are tallied as expenses, if they're worth tallying at all. Weakness doesn't pay. The line must be enforced.
And then, amidst the carnage, and once the stench and smoke have cleared, imagine these powerful paranoid porcinely prideful people being called to account.
"Why would you do such heartless and despicable things?"
And they say: "We swore an oath/signed a pledge. We were driven to this pass, and those that drove us are the ones to blame. We had no choice. What's done is done."