Dunk is jumped and is left bleeding profusely fortunately for him he is strong enough to fight his way out and knock all his assailants out cold, Shiera and Brynden like him bloody. They lick all the remnants of blood off him, sucking his bruised knuckles into their mouths and clearing away all the debris and peeling skin with skilful swipes of their tongues. He keeps insisting it's unhygienic but does nothing to stop them, all he does is pout.
Shiera swipes away his tears when they dig particularly deep, hushing his pained noises and swallowing them down onto her own body. She pushes into the discoloured patches left behind by punches laid into him. Brynden watches and does the same on the other side, both pressing into Dunk's injuries simultaneously. He's sucking his own marks into Dunk's neck, teeth clamping down till they colour Dunk as well.
They drag him to their baths and strip him down to better access his wounds, nothing a few weeks of rest won't fix (or so they tell him, he could just as easily take a week to heal ad be back in perfect health) Brynden washes him down and puts all kinds of hair products into Dunk's hair, Bryden makes sure the body wash he uses carries both his and Shiera's smell, he wants their third to be absolutely claimed in the ways of dragons (scent marking, sharing their resources and being taken care of after battle).
When their done bathing they keep Dunk bare so that they can rub soothing/healing creams into his skin and so that they can wrap any of the cuts left behind (not very deep just surface level).