This enrages the Dragonking.
How dare a vassal state like Shirone refuse an order from the Dragonking!
To show his wrath, the king sent his most able knights, Death God Randolph and the Order of Black Knights, with Pax to initiate a coup.
They murdered the rest of the royal family, and installed Pax on that still bloody throne.
"... And that's how I gained everything. Rank, fame, a woman's love, and the strongest pawn."