The background material mentions hostages a few times but doesn’t really give much context, who were the hostages, why were they left behind etc?
I understand it's been a common practice in our own history, for instance following a peacy treaty, to exchange groups of nobles in order to stabilize the peace. These people are hosted at courts, treated with respect and serve to enhance understanding between the cultures while they also function as hostages. This is how I picture the exchange between Ravenland and Alderland following The Divide. I haven't expanded on who these people were though since this was 1200 years ago. In some yet unpublished material you will however learn that the elven hostage to Alderland more served as councellors and actually interfered in politics when things went bad – not that it helped.
Might hostages be a misleading term?