Based on the context of "The Metamorphoses" by Ovid and "The Tempest" by William Shakespeare, both Prospero and Medea possess the power to manipulate the natural world around them, particularly through their magical abilities.
In "The Tempest," Prospero has control over the elements, including the wind, which he uses to create the storm that shipwrecks his enemies. In "The Metamorphoses," Medea is depicted as a powerful sorceress who can also manipulate nature in various ways, although her specific abilities in the text tend to focus more on her skills in enchantment and transformation.
Given these interpretations, the most fitting response regarding the power they share would be:
They can control wind.