In just a couple of decades, collaborations have opened up a world of possibilities for the world of fashion, with consumers now attuned to the letter X that indicates the marriage of two brands. High-profile collaborations include Prada x Raf Simons and Gucci x Balenciaga, but younger labels are also getting in on the action, as we've seen with La Draft Paris x Apnée. Commercial success is often a given, but the best fusions happen when the brands involved have a shared vision. We take a closer look.