Board Thread:Questions and Answers/@comment-208.54.37.146-20160628231617/@comment-5308269-20160710123948

Perception1 wrote: According to some of the pages, House Arryn has become a vassal of the King in the North and the Valen itself is now part of the Kingdom of the North.

The Vale of Arryn have allied with the North. They're not vassals. And since it was the Knights of the Vale who saved the Stark army at the battle of the bastards, it's pretty laughable to suggest that they pledge themselves to the Starks as vassals.