This system sounds familiar...

[Mike W.]

"The physicist and Nobel Prize winner Owen Chamberlain once proposed an improvement to deterrence based largely on reducing the possibility of a moral hazard, though he didn’t put it in these terms. He wrote to the president of the Federation of American Scientists in the mid-1980s with the following suggestion:

'The idea I want to have looked over is this:

The 200 most important political and military persons in each superpower should be required to provide one family member who could act as a hostage by living inside the other superpower. Thus, every powerful politician or general would have one family member.

I claim this might be arranged easily, is really quite inexpensive, and I believe it has the potential of putting the world in a different frame of mind. It might make nuclear war seem out-of-the-question to all.

The hostages—maybe one can find better word—could be children or grandchildren or perhaps nephews and nieces. We could afford to have excellent schooling for the hostages, for the number involved would be very moderate.

I admit is a gimmick. However, it seems to me to be a gimmick with more than the usual protection for the dollar.'"

Sounds an awful like the medieval system of wards and hostages.

[Sir Patrick]

So true. I forget whom said all the good ideas have already been taken.

[Ian]

Theon Greyjoy

[Sir Patrick]

Reek!  My name is Reek!

[Thorsteinn]

Now imagine if Theon had been written with some other historical examples in mind.

"OK Theon. Time to go home & get your dad on our side."
<later>
"Your not a Greyjoy. Your a Stark! No Ironblood before me but a Northerner!"
"And? You bloodly-well traded me like a cheap horse to save your worthless hide! I thank the Old Gods everyday I ended up with the Stark's. Now you going to side with us or what?"
"Never! Get out of here. You're dead to me & Your sister."
"Is that your final word?"
<much later>
"... so right after our meeting my father & sister had terrible highly unlikely accidents that ultimately proved fatal. Terrible that. Anyway Robb I... Convinced the Iron-Born to go out raiding our enemies & leave our forces alone. Things are looking up!"

[Sir William]

That along with all of the intermarrying amongst the royal houses - all designed to keep things copacetic.  But there was always one with a vision, saw his progeny and family as stepping stones and that whole system failed because of the one.  Kill him though, and everything's back to groovy.