Shirley was designed to be the visual opposite of Melissa; short, blonde, and overtly feminine, hence the bow and barrel curls, which are a lot of fun to draw. Her brassy hair color is a direct reference to Julia from Cowboy Bebop because I correctly thought that rendering it in monochrome would look good.
Jeremy came about because I once heard some friends talking about a super weird pirate character with an eyepatch in a manga and I decided I should make a character with an eyepatch. (I later figured out that I was referencing the pirate captain from Berserk.) I also didn't have a bow user character yet, so. I never settled on a story for how he lost his eye.