In a game of Planechase, suppose we're on Horizon Boughs, which says:
All permanents untap during each player's untap step.
I have Deserter's Quarters out, tapped using its second ability to keep another creature tapped.
You may choose not to untap Deserter's Quarters during your untap step.
{6}, {T}: Tap target creature. It doesn't untap during its controller's untap step for as long as Deserter's Quarters remains tapped.
Would this mean I can choose not to untap Deserter's Quarters during the untap step, and keep the other creature tapped, or do both of them untap anyway?