Whatever character in the politics you pick and send a mission, it will just give you random result that may be slightly affected depending on the relations you and the faction have.
But still, even your wife/son/brother sent to an ally, can "betray you" for no reason.
Even worse, sometimes the faction will kill your diplomat, which has a descent chance of happening even with yellow factions, which again is insane, it will even kill your wife/son/brother.
Now look, I get this happened in real history, but it had some actual circumstantial context, what never or rarely happened is a ruler killing randomly another rulers son on a diplomatic mission, or a rulers closest family just for no reason betraying him on this one diplomatic mission. If my son betrays me it should be a part of something, not just a random dice roll.
This is just typical lazy CA, they just put some half-baked mechanic so you have things to click in the character screen, and they can call it a feature, when its a bare skeleton of one.