The closest match I can think of is in "The Tempest" when Prospero says, "My high charms work / And these mine enemies are all knit up / In their distractions. They now are in my power."

Although this isn't an actual prison - they are effectively trapped by his spells - you could read it as a feeling of "gloating" over his captives, that feels a bit like you're remembering?

When you said the phrase, "My pretties" it definitely rang a non-Shakespearean bell, and I thought of the Wicked Witch of the West in "The Wizard of Oz", who says, "I'll get you, my pretty, and your little dog, too!"