I had very little to go off of for these two; I knew they were the geniuses behind Columbia, I knew that they were "twins," and that maybe they should be redheads "because we don't have any redheaded characters yet." I ended up landing on designs that were somewhat aloof and checked out, which worked extremely well considering their role in the game itself. Rosalind is based roughly on the Gibson Girl, and Robert on the Arrow Collar Man - the two unattainable ideals at the beginning of the 20th century.
I'm a huge fan of the popularization of masculine tailoring in women's clothing during the late Victorian and Edwardian eras, and wanted to reflect that in Rosalind's costume; once she was finalized, Robert's suit was designed to match.