"Your Majesty stand down, the man is no threat." if Derendil continues Dustin fires a poisoned bolt hoping to put the royal to sleep. Aiming for non lethal areas on Derendil.
Bonus action to Hide.
His next action is to fire another bolt if the first didn't put Derendil to sleep. Once again aiming for a but cheek or someplace non lethal.
He will move to another location and as a bonus action hide again.
Rolls
Hand Crossbow - (1d20+7)
(16) + 7 = 23
Hand Crossbow Damage - (1d6+5)
(6) + 5 = 11
Sneak Attack - (2d6)
(55) = 10
Hide - (1d20+9)
(3) + 9 = 12
Hand Crossbow - (1d20+7)
(16) + 7 = 23
Hand Crossbow Damage - (1d6+5)
(2) + 5 = 7
Sneak Attack - (2d6)
(66) = 12
Hide - (1d20+9)
(10) + 9 = 19