Might one please ask if you find it at all ironic that House Arryn “the highest, purest line of Andal nobility” intermarried with House Hunter (a House of the First Men) within two generations of The Battle of Seven Stars? (Also that newcomer Ser Artys Arryn was almost certainly named for the native Hero Artys, who slew the Griffin King).

Definitely. Although you could see the dynastic politics at work – House Hunter had been one of King Robar Royce’s chiefest bannermen in the attempt to retake the Vale for the First Men, so marrying into that House strengthens House Arryn and divides its potential enemies. 

Then again, we know so little about the Vale’s internal development between the rise of the Arryn Kings and Robert’s Rebellion, especially in comparison to their foreign policy. 

A brief digression on that: thinking about it, I’m sort of surprised there isn’t more animosity between Northmen and Valemen similar to the Reach/Dorne animosity, given the thousand year war the two sides fought, the ethnic and religious divisions between them. I suppose you could say that ties have been repaired with marriages – between the Starks and the Royces and Rogers, for ex – and fosterages (Ned, Domeric Bolton), but where did this policy come from? How successful was it, among the highborn and the smallfolk?