“I would describe Patrick’s work as like distilling something to the purest form,” said Kate Mulleavy. “Laura and I are so quiet about how we communicate with people. We like to work in isolation when we are working on the collection. So the first person we talk to about what we are doing is Patrick.”

Mr. Li designs the fashion show invitations that are mailed to hundreds of editors and store buyers each season, enticing them to see a collection and sometimes giving them a hint of what is to come. Ms. Mulleavy said that she and her sister typically fire off a mountain of inspirations. The spring collection, for example, was based on transformation myths involving a person who is burned alive and reborn as a condor or a vulture. There was talk of California condors, burnt sand and the wildfires that were spreading around Los Angeles while the Mulleavys were at work.

“Their references each season are totally off the wall, and sometimes I think they are meant to confuse,” Mr. Li said. “You can leave the discussion thinking, ‘Oh, I don’t really know what it means for a California condor to intersect with a Robert Smithson earthwork,’ but each of those things imparts a certain feeling.”

Mr. Li described several failed attempts to actually burn the heavy stock used for the Rodarte invitations, ultimately giving up when a printer refused to take the insurance risk. Instead, he used a silk-screened adhesive that was coated with burned sand. The Mulleavys liked the idea so much they decided to put sand on the runway as well. Mr. Li also helped the designers adjust their logo, from a basic all-caps style produced on a typewriter to one that looks slightly more ominous, using a bolded version of a Times font that has been condensed so severely that the letters start to vanish.