The Avvars, a group of independent small tribes, have been fighting with Trevinter over land. With the tribes being independent, their is no unity in their actions. It is not surprising a group of rogue Avvar took over Hargrave Keep and were unwise to hold some of the Inquisition soldiers hostage. Then, in a move that was beyond stupid, issued an ultimatum to the Inquisitor to fight them and rescue the soldiers.
An unexpected event happened. Movran the Under, father of his “idiot son” Hand of Korth (his words, not mine) who was killed in the battle rescuing the Inquisition soldiers, attacked Skyhold. I honestly had no words watching the scene unfold.