Roy doesn't necessarily support the Queen, but he also doesn't want what appears to be an angry crazed begotten son seizing the throne and sending everything into potential chaos because he's mad. He prefers Kea's plan, but finds it pretty naive, and so he's settling for stability over anything else. He'll spend most of his time in the Palace buffering defenses and talking King's men into laying down arms with his power.

He might also hop into the rifts for hahas, depending on who else goes. He's been there, done that in jumping into doomy dimensional portals, thanks.